STUDY OF THE BEHAVIOR OF LIP SEALS IN PNEUMATIC ACTUATORS

The simulation of pneumatic actuators needs a knowledge of friction fo rce under changing of the operating conditions. Friction force depends on a number of factors, including operating pressure, seal running sp eed on the cylinder barrel and road, barrel material and surface rough ness, seal dimensions and profile, seal material, lubrication conditio ns, cylinder distortion during assembly, and operating temperature of actuator components. This paper shows a system for measuring the frict ion force caused by a lip seal used in pneumatic cylinders. Measuremen ts are made in order to assess the influence of seal material and dime nsion, barrel material and surface finish, and operating conditions on friction force. Results of experimental tests show that seal friction forces for grease-lubricated service are clearly dependent on speed a nd pressure and are less sensitive to other parameters, i.e., barrel m aterial and roughness, seal material, and profile. Finally a compariso n among different kinds of seals is made by means of proper sensitivit y coefficients.