果蔬包装机凸轮连杆式切断机构运动分析与优化

Motion Analysis and Optimization on Cam-link Cutting Mechanism of Fruit-vegetable Packaging Machine

针对目前果蔬包装机中存在切刀刮膜和切口不正等问题,提出了一种基于连杆机构和凸轮机构的果蔬包装机切断机构。建立了切断机构的运动数学模型,并以此为依据建立了切断机构基于ADAMS的参数化模型,得到该机构主要参数变化对机构运动的影响规律。通过二次规划算法优化分析计算,得出一组最优参数组合。利用此参数组合的运动学仿真分析表明,下切刀的加速度最大值为7 971 mm/s2,切割距离为20.4 mm。根据优化结果加工组装试验样机,以PVC膜切断率为主要检测指标对该试验样机进行试验,结果表明,对11、12、13μm 3种厚度的PVC保鲜膜切断率都在98%以上,切断机构满足果蔬包装机作业要求。

Nowadays,aiming at the problems of packaging film scraping and incision deviation caused by the cutting mechanism in the fruit-vegetable packaging machine,a cutting mechanism of fruit-vegetable packaging machine based on the linkages and the cam mechanism was proposed. Firstly,the motion mathematical model of the cutting mechanism was established. Then,by using the virtual prototype of ADAMS,the parametric model of movement characteristics of cutting mechanism was completed according to these mathematic equations. And the influence of the main parameters of the mechanism on the movement of the mechanism were analyzed,including the link length of l1,l2,l3 and rise rotation angle β of the cam.Meanwhile,depending on the analysis method of sequential quadratic programming( SQP) algorithm,the optimal aggregative index could be obtained under the condition that l1 was 247 mm,l2 was 154 mm,and l4 was 139. 5 mm. In this situation,the kinematic simulation analysis showed that the maximum value of acceleration of the lower cutter was 7 971 mm / s2,and the cutting distance was 20. 4 mm. Finally,based on the above simulation and analysis,the prototype was processed with the optimized parameters. And the prototype test using the PVC film cutting rate as the main indexes was carried out. The results showed that the cutting rate was above 98% for the PVC film with thickness of 11 μm,12 μm,13 μm,which indicated that the cutting mechanism could satisfy operation demand of the fruit-vegetable packaging machine.