Abstract: Based on the equivalent principle of the influence of rounded punch and edge stress concentration theory, this paper proposed a dynamic friction characteristic model of single through hole that the shape of the contiguous border is changing precisely. Simultaneously, by means of introducing the coupling principle of multiple sets of through holes, the friction characteristic model was established when there were multiple through holes in the valve sleeve. By comparing the friction characteristic model with the experimental results, the micro-gap reciprocating dynamics frictional characteristic of the contact surface between the through hole of the valve sleeve and the valve body seal ring of the pneumatic valve were studied. The results showed that the friction characteristic model was feasible and effective. The edge stress concentration effect produced by the through holes has a great influence on the friction characteristics. The frictional force of the sleeve containing the through hole is higher than that of the non-perforated sleeve. Mass friction increases with the growing of length of the contact line of the through hole. The increase of the fillet radius can decrease the frictional force on the sealing surface of the through hole. The greater the fillet radius is, the more obvious the impact is.

Key words: hydraulic and pneumatic, pneumatic control valve, through hole, frictional characteristic, stress concentration effects