Flow Field Analysis And Oscillation Control Of Scroll Vacuum Chuck

As a new type of pneumatic vacuum end-effector,the scroll non-contact vacuum cup based on the principle of vortex flow has the advantages of non-contact in absorbing and transporting workpieces,besides the simple vacuum generating circuit.However,there is still no perfect theory for describing the complex flow field inside the sucker,and there is no clear index for evaluating its performance now.In addition,the unstable turbulent flow field inside the sucker will cause the workpiece to oscillate when it absorbs the workpiece and easily touch the workpiece,thus polluting and damaging the workpiece surface.The following aspects of research are carried out to solve these problems:At first,based on the theoretical study of the swirl flow formed by the suction cup,combined with the static suction characteristic curve and the dynamic displacement characteristic curve of the swirl vacuum cup,a comprehensive evaluation system including three performance indexes is established:the maximum suction force F_max,the support stiffness K_l and the displacement overshoot?_p,which are taken as the structural optimization objectives of the swirl vacuum cup.By analyzing the process of swirl flow,two key structural parameters are proposed:the angle?between the normal line of the plane where the tangential nozzle is located and the axis of the sucker;the diameter d of the tangential nozzle.Secondly,the pressure and velocity distributions of the flow field inside the sucker are studied by numerical simulation,and the effects of two key parameters on the comprehensive performance are deeply explored by experiments.It is concluded that a small inclined tangential nozzle plane can improve the internal non-uniform flow field;under the same flow rate,the smaller the diameter of the tangential nozzle,the larger the sucker suction force and support stiffness,but the smaller the diameter of the tangential nozzle,the smaller the suction range.According to the results of simulation and experiment,a new type of scroll vacuum sucker is designed and manufactured,which can reduce the oscillation.Finally,the idea of reducing the workpiece's oscillation during suction under PID control is put forward.Its theoretical feasibility is verified by simulation.The hardware platform of the position closed-loop system of the scroll vacuum cup is built,and the software system is designed.Finally,the displacement overshoot of the suction cup is reduced and the stability of the suction is improved.