指夹式玉米免耕精密播种机振动特性及对排种性能的影响

为研究2BMZ-2型指夹式玉米免耕精密播种机在免耕地表作业时的振动特性及振动对排种器排种性能的影响规律,建立了整机振动特性模型,求解其稳态振动响应;测试播种机在免耕地表作业时排种器振动特性。搭建振动排种试验台模拟田间作业振动环境,测试机械振动对排种器性能的影响规律,并运用高速摄像和与图像目标追踪技术研究籽粒落种运动规律。结果表明,播种机的振动特性主要决定于作业速度、地表及土壤情况和播种机的结构特性。播种机前进速度在5～9 km/h范围内,播种机振动能量的频率分布主要集中在低频段的3～11 Hz;前进速度越大,振动加速度越大,但不影响振动能量的频率分布。机械振动对排种器充种性能无显著性影响,对播种性能具有显著性影响的试验指标为播种合格率、粒距纵向变异系数和粒距横向变异系数(P0.05);试验因素对排种均匀稳定性影响的主次顺序为排种轴转速、振动加速度、振动频率;各试验因素的增大均使籽粒下落轨迹及落点更加离散、落种范围增大,且增大排种轴转速使落种点位置逐渐远离投种初始位置。该研究为免耕播种机指夹式排种器排种性能的提高提供了参考。

Vibration characteristics of corn no-tillage finger-type precision planter and its effect on seeding performance

Conservation tillage is an important measure to promote the sustainable agriculture. No-tillage sowing in straw-covered fields is an advanced farming technology of conservation tillage system, which has been widely used in northeast China because of its many advantages, such as saving production cost, protecting soil and ecological environment. However, due to the long growth cycle of corn, the straw is stronger and harder to rot. During the harvest operation in autumn, corn stalks are usually crushed by combine harvesters and scattered on the ground, but the length of the stalks crushed is inconsistent and the distribution is uneven on the ground. During the sowing operations in spring, the crushed straws are not rotten in the field, the surface flatness is relatively poor, and the sowing operating environment is worse. No-tillage finger-type precision planter is widely used in straw mulching for seeding, the above problems results in the random vibration excitation of the no-tillage planter during the operation is significantly enhanced, which seriously affect its performance, such as affecting the working quality of planters, reducing the seeding yield and uniform plant distribution, and ultimately reduces crop yields. In this paper, in order to study the vibration characteristics of 2BMZ-2 corn no-tillage finger-type precision planter and the influence of vibration on the seeding performance of corn finger-type precision seed metering device, the vibration characteristics model of the planter was established and the steady-state vibration response was solved. The vibration characteristics of the planter worked in straw mulching were measured and analyzed by field test. Based on the above theoretical analysis and field test results, a test bench for vibration seeding was built, which was used to simulate the vibration environment of the field operation and to test the influence of mechanical vibration on the performance of the seed metering device. The three-dimensional space trajectory of the falling seed was measured and analyzed by the high-speed photography and target tracking technology. The results showed that the vibration characteristics of the planter were mainly determined by the working speed, the surface of field, the soil conditions and the structural characteristics of the seed metering device. The field experimental results showed that when the working speed was in the range of 5 to 9 km/h, the vibration frequency distribution of the seed metering device vibration energy was mainly concentrated in the low frequency range of 3 to 11 Hz; the greater the working speed was, the larger the vibration acceleration was, but the vibration frequency distribution of vibration energy was not affected. The bench comparative test results showed that the mechanical vibration had no significant effect on seed filling performance of the seed metering device, but had significant effect on seeding qualified rate, coefficient of variation of spacing in longitudinal direction and coefficient of variation of spacing in transverse direction. The multi-factor quadratic general rotation combined test results showed that rotational speed, vibration acceleration and vibration frequency were the main and secondary factors influencing the uniform stability of seed arrangement, reducing the vibration acceleration can improve working quality of the seed metering device more than reducing the vibration frequency. The single factor experiment showed that, in the range of vibration frequency of 3 to 11 Hz, vibration acceleration of 0.3g to 1.5g and rotational speed of 31.5 to 57 r /min, the increase of each test factor made the seed falling trajectory and the seed falling points more discrete, and increased the range of seeding. In addition, increase the rotational speed made the position of seed falling point gradually away from the initial position of seed. The results can provide guidance for the design of the vibration-damping system of the corn finger-type precision seed metering device and corn no-tillage finger-type precision planter.