高留茬玉米秸秆复式割台粉碎还田装置设计与试验

为了在玉米摘穗的同时,将秸秆上半部分回收作饲料,下半部分实现高质量粉碎还田,在4YZQ-2B1型穗茎兼收玉米收获机割台的下方增加了锯盘式玉米秸秆粉碎装置,通过对圆锯片运动及切割机理等的分析,利用ADAMS对此复式割台进行了参数优化和运动分析,并在Pro/Mechanica中,对锯盘刀轴进行了有限元模态分析,得到其固有频率。确定采用平面锯身整体式横截圆锯片,直径为180~380mm,厚度分为1.2、1.5、2mm 3种,锯片间距为50mm,齿形为等腰三角斜磨齿,齿高为7.5mm,两刀辊中心距为760mm。高留茬玉米复式割台田间试验结果显示,当机组的作业速度为2m/s,刀辊转速为850r/min时,秸秆粉碎长度合格率为92.14%,留茬高度平均值为52.18mm,均满足秸秆还田机作业标准,能够对玉米秸秆离地粉碎,减轻了刀具的磨损、提高了玉米秸秆还田质量。

Design and Experiment of Smashed Straw Unit for High Stubble Maize Double Header

At present, the main mode of maize straw returning is total returning, which has large amount of returning and stubble is not perishable after burying straw. The operation mode of corn straw grinder is near ground crushing, in the process of crushing, the blade is inevitably exposed to soil and worn quickly, which leads to the poor quality of straw pulverization. Therefore, a comprehensive utilization plan of corn straw was put forward. When the corn was harvested and picked, the straw above the ground must be recovered and the remaining must be cut off back to the field. On this basis, the double header was designed on the 4YZQ-2B1 type corn harvester for reaping both corn stalk and spike. The saw-disc pulverizer was added below header, circular saw blades were adopted by the device and arranged in inverted cone, the diameters of blades were gradually reduced from top to bottom. Linear speed of the tooth tip of saw blade tip was proportional to the diameter of circular saw blade, during the process of cutting corn straw, there was a relative velocity between the adjacent saw blades. It had the effect of tearing while cutting straws, which was more beneficial to the pulverization of straw and the subsequent decay. In addition, maize straw was crushed by the circular saw blade while upright, and the saw blade was not exposed to soil to reduce wear. The saw tooth of the saw blade can keep sharp for a long time to ensure the effect of straw sawing and crushing. Combined with the movement and cutting mechanism of circular saw blades, the influence of saw blade thickness on sawing, and the height and amount of saw blade teeth on cutting and re cutting were analyzed emphatically. At the same time, the parameter optimization and motion analysis of double header was carried out by ADAMS. The operating parameters of the two rows of picker rollers were analyzed to ensure the consistency of the harvesting monomers in two rows. The trajectory of effective working height of circular saw blades with diameter of 180mm was analyzed. The result showed that there was a coincidence between the track lines. The saw-disc pulverizer would not produce leakage during operation. Through the Pro/Mechanica in Pro/E, the first order vibration mode of saw blade shaft was simulated, and the natural frequency of saw blade shaft was analyzed. In order to eliminate vibration, trying to let the external excitation and avoid natural frequency or minimize the excitation of natural frequency. The plane saw body integral circular saw blade was adopted by the saw-disc pulverizer, the diameter was 180~380mm, and the thickness was divided into 1.2mm, 1.5mm and 2mm. The tooth shape was isosceles triangular profile bevel gear tooth with height of 7.5mm. And the center distance of the two knife roller was 760mm. Field experiments on qualified rate of chopping length, returning amount and stubble height of high-stubble maize double-header were carried out. The results showed that the qualified rate of straw chopping length was 92.14%, average stubble height was 52.18mm when working speed was 2m/s, rotation rate of the knife roller was 850r/min, all test indicators were satisfied with standards of straw stubble machine, and the amount of returning to field was 30% to 40% of the full amount, it can achieve the corn stalks smashing from the ground and completely chopping of straw fiber and improve the quality of corn stalks returned to soil. The quality of corn straw returning to field was improved, and the problems of blade wear and poor quality of straw chopping were overcome.