A pneumatic cylinder system of compressed air as a working fluid has a variety of advantages such as low price, high respondence, non-explosion and good control performance and thus has many applications in the field of automobile, electronic and semiconductor industry.
However, it has a difficulty in controlling a precise position due to quick response of system and compressibility of working fluid and, in particular, shock stress may occur due to an external load, resulting in fracture of a cap unless cushion device is equipped in the cylinder.
To avoid this, a cushion device should be installed for damping effect of the external load and supply pressure as for decreasing shock stress and vibration caused by high speed rotation.
A physical and mathematical model of a double acting pneumatic cushioning cylinder is presented, which is based on the following assumptions ;
ideal equation of state, isentropic flow through a port, conservation of mass, polytropic thermodynamics, single degree of freedom piston dynamics, and energy conservation.
These differential equation can be solved through numerical integration using the fourth order Runge-Kutta method.
An experimental study was conducted to validate the results obtained by the numerical integration technique.
Simulated results show good agreement with experimental data.
The computer simulation model presented here has been extremely useful not only in understanding the basic cushioning mechanism but also in evaluating different designs.
Finally, the velocity of pneumatic cylinder system with multiple orifice cushion sleeve is set vertically controled with the meter-in/out system.
This study examines the dynamic characteristics of pneumatic cylinder which are used as cushion devices.
It turns out that the cushion pressure is mainly a function of the external load rather than the supply pressure.
The cushion region characteristics was also revealed in the meter-in circuit.