双系统中小粒林木种子精量播种机的设计

Design of Double System Precision Seeder for Small and Medium-Sized Tree Seeds

为实现对种壳脆硬、球度低、形状不规则的中小粒林木种子的精量播种,设计基于气吹-振动双重作用供种的精量穴盘播种机。以樟子松种子为例,应用压痕法、反相分析运算法则、EDEM(最专业的颗粒系统仿真软件)中的Hertz-Mindlin模型等方法,探究其力学特性和建立种子的种群空间形态模型,据此应用SolidWorks进行播种机结构设计。该播种机主要由气动系统、电控系统、穴盘、播种机构、供种机构、压穴机构和穴盘输送机构等组成。其供种系统设有气吹-振动组合式种子流化装置,通过气吹和振动的双重作用使种子颗粒群有效分离,在气流的连续作用下种子持续保持“沸腾”的运动状态,确保吸附取种过程中,种子能相对稳定地处于有效吸种位置,从而提高设备的吸附成功率。经播种试验,当种盘振动频率为20 Hz,振幅为5 mm,穴盘输送速度为0.045 m/s时,其空穴率最低,为1.74%,重播率0.26%,播种合格率98%,穴播速度可达到300盘/h。通用性强,可匹配硬质常规穴盘和纸质蜂窝穴盘。

In order to realize precision sowing of the small and medium-sized tree seeds, which with brittle and hard shell, irregular shape and low sphericity, a precise seeder which based on blowing-vibration and match seedling trays was designed. Taking Pinus sylvestris var. mongolica seed for example, the application of indentation method, inverse analysis algorithms, the Hertz-Mindlin method which from EDEM as model were used to explore the mechanical properties and establish the population spatial configuration model of seed. Based on this, SolidWorks was applied to design the structure of the seeder. The seeder was mainly composed of pneumatic system, electronic control system, seedling trays, seeding mechanism, seeds supply mechanism, punch mechanism, seedling trays conveying mechanism and so on. The seeds supply system was supported by blowing-vibration device, which could make seeds group effective separation and flow, keep the seeds movement state such like “boiling”, ensure that the seeds can be relatively stable in the effective seed suction position during the seed adsorption, so as to improve the adsorption success rate of the equipment. Through sowing experiment, when the vibration frequency of trays was 20 Hz, vibration amplitude was 5 mm, and running speed of trays conveying mechanism was 0.045 m/s, the cavity rate was the lowest 1.74%, repetitive seeding rate was 0.26% while the qualified rate of sowing was 98%, the sowing efficiency was 300 tray/h. The precision seeder which have strong versatility can match hard conventional seedling trays and paper alveolate seedling trays.