Design And Reliability Research Of Automatic Assembly Mechanism For Prefilled Syringes

With the growing global demand for vaccines,especially the surge in the demand for COVID-19 vaccine caused by the outbreak of COVID-19 virus in the past two years,the demand for single-use prefilled vaccine syringes has been increasing rapidly at home and abroad.The automatic assembly mechanism for prefilled syringes is a high-speed automatic equipment for the combined assembly of prefilled syringes.The key actuator of the equipment is the casing assembly mechanism.Reasonable structure design of casing assembly mechanism and its motion precision reliability determine the quality of prefilling syringe assembly products.This paper takes casing assembly mechanism as the research object,the structural design is carried out,the motion reliability of the mechanism under the influence of multiple factors is studied,and the motion of the mechanism under the rigid-flexible coupling state is analyzed.The main research work of this paper is as follows:According to the design requirements of casing assembly mechanism,the cam-linkage mechanism is adopted.The CAM contour curve was obtained by calculation,and the digital prototype model of casing assembly mechanism was established.Based on the digital model of the casing assembly mechanism,the kinematics simulation analysis of the casing assembly mechanism was carried out,and the kinematics performance curves at the key points of the mechanism were obtained.Based on the casing assembly mechanism motion analysis,the roadway is modified,keeping the displacement and moving distance of roadway constant,but the previous slope design is modified to similar to the sine acceleration in the design of CAM design,the modified motion analysis results show that the velocity and acceleration of the end-effector are stable,and there are no sharp points and sudden changes.Taking the original size error,clearance and wear as the influencing factors,the motion error model and reliability model of the casing assembly mechanism were obtained,and the motion error curves and reliability curves of each part of the casing assembly mechanism were calculated;The results show that the casing assembly mechanism is within the reliable range,while the original size error has a greater influence than the other two factors,and the effect of the lifting and clamping mechanism is greater than that of the down-cam mechanism.Therefore,for the design and manufacture of subsequent casing assembly mechanism,we should pay more attention to the influence of original size error and the influence of lifting and clamping mechanism.Based on the rigid-flexible coupling dynamics analysis platform,the rigid-body model of the casing assembly mechanism was established,and the kinematic performance curves of the casing assembly mechanism under ideal and clearance conditions were obtained by simulation;At the same time,the rigid-flexible coupling model of the clamping link in the casing assembly mechanism was established combined with the finite element analysis platform,and the kinematic performance curves of the end-effector under ideal condition and clearance condition were obtained by simulation.By comparing several groups of curves obtained by simulation,the results show that the larger the clearance is,the greater the fluctuation of the velocity and acceleration curves of the mechanism is,and the fluctuation degree of the flexible curve is different from that without considering the flexible curve,and the acceleration fluctuation of the flexible curve has a certain convergence.Therefore,in the design of casing assembly mechanism in the future,the effect of not only the clearance but also the flexibility should be considered.