DYNAMICS OF PULSED HOT-PRESSING FOR POWDER MATERIALS

Mechanical interaction of impact machine and porous-viscous body is analyzed. The result is a dynamic third order system having two control parameters which are the ratios of elastic stiffness to the weight of the impact parts of the machine and the friction coefficient which depends on bulk viscosity and porous material dimensions. An overall description of process dynamics by the method of phase portraits is developed. It is shown that with low initial powder-blank densities in the initial stages compaction is aperiodic. When a certain increase in density is achieved the motion becomes periodic and it appears on velocity-acceleration coordinates as a stable focus converging to an attractor which is located at the point of rest. With pulsed extrusion a circular attractor arises and a limiting cycle is generated representing pulsed motion and allowing impact energy to be exhausted during extrusion. Theoretical design makes it possible to determine equipment parameters and automation for pulsed hot pressing and extrusion of powder materials.