横向热封切断机构设计与优化

Design and optimization of the transverse heat-sealing-and-cutting mechanism

因横向热封切断机构无法与送膜机构的速度精确匹配,导致横向热封切断时切刀刮膜。为提高生产效率和包装产品质量,提出了一种用于枕型包装机热封切断的凸轮连杆组合机构。通过引入凸轮来封闭机架长度可变的四杆机构,完成了凸轮连杆机构的概念设计。为获得精确的凸轮轮廓和最优连杆长度,在凸轮连杆机构几何运动方程的基础上,建立了以轨迹误差为最小的优化数学模型。最后利用修正的遗传算法,进行目标函数的全局最优搜索,获得了最优凸轮轮廓及连杆长度。试验显示,凸轮连杆机构与目标轨迹上20个轨迹精度控制点的平均误差值仅为0.7 mm。同时水平匀速直线段上精度点与目标轨迹上精度点完全重合。

Since the transverse heat-sealing-and-cutting mechanism cannot accurately match the speed of the film feeding mechanism,the cutting head will scrape the film when the task of transverse heat-sealing-and-cutting is conducted.In this article,in order to improve the production efficiency and the quality of packaged products,a cam linkage mechanism is worked out for transverse heat-sealing-and-cutting.A cam is introduced to close the four-bar linkage mechanism with variable frame length,and thus the conceptual design of the cam linkage mechanism is completed.Based on the geometric motion equation of the cam linkage mechanism,the optimal mathematical model with the smallest trajectory error is set up,so as to identify the accurate cam profile and the optimal linkage length.Finally,by means of the improved genetic algorithm,a global optimal search is performed on the objective function,and the optimal cam profile and the linkage length are obtained.The simulation results show that the average error value of the 20 accuracy-controlling points on the coupling curve and the target trajectory is only 0.7 mm.At the same time,the accuracy-controlling points on the straight line with uniform speed completely coincide with those on the target trajectory.