DYNAMICS OF SUB-CRITICAL MODE OF PNEUMATIC MECHANICAL DRIVES OF PERCUSSIOM MASHINES

Abstract

The task of improving the reliability of pneumatic percussion machines has always been and is still being topical including those equipped with drives with pneumatic mechanical control systems. This applies to both supercritical and sub-critical modes of operation.This article studies the sub-critical regime. In order to establish the stability of the above-mentioned drive, the dynamics of pressure changes in its working chambers in the phases of their filling and emptying with the use of a steady time of the inertial link, the magnitude of the conduction of the inlet element of the pneumatic mechanical control system, the coefficient of flow of air distribution, and the stepping function, were investigated. The pressure ratio when filling the pneumatic chamber at sub-critical mode of energy supply and the function of the pressure ratio when emptying pneumatic chamber at sub-critical mode of exhaust air were examined.Using the obtained research results, it is possible to significantly influence the stability of the operation of the pneumatic mechanical drives in the sub-critical mode by rationally selecting the sizes of the structural elements of the pneumatic mechanical air distribution system and the parameters of the working and compensation chambers.It is proved that in the course of research it is also necessary to take into account the specificity of the contact interaction of the valve stem with the piston-drummer. After all, the reliability of the actuation of the valve mechanism at the beginning of the inlet-release phase of the energy carrier significantly depends on the reliability of the percussion machine during its operation.