打结器割绳脱扣机构与绕绳机构作用分析与改进设计

Analysis and Modification of Interaction between Wiper Mechanism and Billhook Mechanism for Knotter

摘要:

针对打结器脱扣失效和刚性碰撞的问题，分析割绳脱扣机构与绕绳机构的相互作用机理，仿真刀臂的受力—形变，得到刀臂沿打结嘴轴方向的刚度为801.05N/mm，脱扣凹槽与打结嘴的过盈量合理设计范围应为[0.38mm, 0.59mm]；同时得到最大正压力下割刀在刀臂变形后与Oxy、Oxz和Oyz平面夹角变化分别为0.659°、0.4759°和0.4555°，这为割刀安装补偿量提供数据支持；依据刚—柔碰撞原理，设计一种弹性化打结嘴轴系，仿真得到该轴系使脱扣凹槽—打结嘴首次接触力在脱扣和回程阶段分别比原轴系减小46.3%和83.9%，因此该方案可减轻碰撞，同时具备提升脱扣率的优点，最后成功试制样品，实际打捆试验证明了该方案的可行性。

Abstract:

The purpose of this paper was to study and modify the interaction between wiper mechanism and billhook mechanism to solve wiping failure and rigid impact problems. Firstly, load-deformation of wiper was simulated. The results indicated that the stiffness of wiper along billhook shaft direction is 801.05N/mm and the interference between wiper and billhook should be in the range from 0.38mm to 0.59mm. Furthermore, under the maximum pressure, the angles of knife that was mounted on wiper, were changed with Oxy plane, Oxz plane and Oyz plane, which were 0.659°, 0.4759° and 0.4555°, respectively, so it gives a data support for knife installing compensation. Based on rigid-flexible collision theory, a new improved design with elastic billhook shaft system was introduced. The new design used a compression spring that enables the billhook to move elastically and slightly along the shaft direction. Meanwhile, the new billhook system would not affect billhook bevel gear’s movement, since the spring keeps the gear on its original position continuously. Simulation results demonstrated that the design could reduce initial contact force between wiper and billhook by 46.3% and 83.9% at wiping and return phases, respectively. Therefore, the design can decrease impact, and it has a theoretical advantage of increasing knotting rate. Finally, a prototype of the design was produced and its feasibility was verified by actual baling experiments.