Pneumatic cylinders are widely used for mechanical handling. For velocity control of pistons, meter-out restriction method is used in many cases. Piston velocity is determined by the ratio of restriction area and piston area. When the air in the cylinder is discharged, temperature of air decreases steeply. In the case of normal operation, piston velocity is influenced by air temperature change in the cylinder. When air cylinder is used in low temperature field, restriction of the cylinder sometimes freezes and cylinders do not function.
This paper shows air temperature change in cylinder and its effect on piston velocity using a new mathematical model. This new model is composed of the equation of piston motion, continuity equation of air mass and energy. In the energy equation, temperature change is calculated using heat transfer between air and the cylinder wall.
In this research pneumatic cylinder moving tests have been conducted for different loads and supply pressures. To examine the temperature change effect on the piston velocity, a particular set up is devised. This method is to vary the temperature by changing the initial air pressure of cylinder discharge side. By experiments the effect of temperature change on piston velocity is made clear and the validity of the proposed model is confirmed.