Research On Self-adjusting Cushion Pneumatic Cylinder

As commonly used pneumatic actuators,cylinders' dynamic performance is of great significance to improve production efficiency in the process of modern automation and intelligent development.Cushion structure is the key technology in cylinder design.The cushion structure with needle valve or relief valve is adopted in existing cylinder products.According to the working condition,existing products of cylinders can get better cushion performance by adjusting the opening of needle valve or relief valve.Cushion adjustment takes too much time and effort.When conditions of gas supply pressure,load and opening of speed controller change,cylinders' cushion state is destroyed,and the phenomenon of impact and rebound appears at the end of stroke.This will shorten cylinder service life and reduce the efficiency of the work.So the aim of this thesis is to design a self-adjusting cushion cylinder adapting a wide range of working conditions without adjustments.The experiments with a relief-valve cushioning cylinder were conducted.The analysis on cushion characteristics under the different work conditions of gas supply pressure load and opening of speed controller revealed the mechanism of cushion damage.The cushion area change curve is calculated by using the various cross-section of exhaust self-adjusting cushion design idea.Cushion begins when the area of the cushion cavity is less than the exhaust area of the speed controller.So the cushion start point is related to the exhaust area.The cushion length determines the cushion energy.The exhaust area and cushion length are calculated based on speed and the cushion area change curve is got.Then the self-adjusting cushion structure is designed.A self-adjusting cushion cylinder is designed based on the self-adjusting cushion structure.The cylinder is assembled and experiments with the cylinder are done.The correctness of cylinder design is proved by measurement experiments of the lowest use pressure and leakage.The experimental results of cushion characteristics prove that the variable cross-section of exhaust design idea based on cushion starting point is correct.The cylinder has self-adjusting cushion feature in the work conditions of gas supply pressure variation from 0.4 MPa to 0.6 MPa and load variation from 6.48 kg to 21.48 kg.