Dependence of final mean density on initial medium length in dynamic powder compaction with elastic punch and plug - multishock compaction of a copper powder medium in a die by punch impact V

摘要

In the previous study, the analysis of the multishock compaction processes of a die-contained copper powder medium, supported by an elastic plug at one end and impacted by an elastic punch at the other end, showed a mean green density (ρ{sub}(mean)* )-initial medium length(S*) curve with a complicated waveform, where the first and second critical length's, S{sub}(cr1)* and S{sub}(cr2)*, were included. This analysis was performed for a constant sum of the lengths of the medium and plug S{sub}1*. In this study, it is clarified in the same example as in the previous study that the waveform is caused by shock waves and unloading waves transmitted in the medium from the plug, whose number is increased with an increase in the medium length. In the second critical length the shock waves, which are weakened by the unloading waves and die wall friction, cause a maximum increase in density. Furthermore, approximate similarity conditions for compactions with various S{sub}1* values are presented. They are given by two fixed parameters, punch mass M* and initial punch velocity v{sub}0 in the region S* (1/2) S{sub}1*. The calculated ρ{sub}(mean)*-S* and ρ{sub}(mean)*-S*/S{sub}1* relations support these conditions.