粉体の圧縮成形理論

粉末金属部品の成形に関する研究 (第3報)

抄録

It is necessary to establish the theory of compacting metal powder in order to analyse the stress and density distributions in the compacts which influence the mechanical preperties of sintered machine parts.
The authors explain the mechanism of compacting metal powder and try to establish a theory of the process, that is, a powder mechanics by obtaining some mechanical properties of metal powder substances experimentally.
The results of theoretical and experimantal approaches are as follows :
(1) It is experimentally proved that the Mohr's theory holds well on the theory of compacting metal powder. Then, it is considered that the mechanism of compacting metal powder is the shearing slips of powder particles, which cause the maximum principal strain, being accompanied with the increment of the density.
(2) By the Mohr's theory, the critical shear stress gives the relation between the principal stresses and determines the stress state in the metal powder substances. The relation of the critical shear stress τ₀ to the compressive stress σ on the shear plane is expressed by the exponential function.
(3) The compacting density ρ of the powder substance is determined by the maximum principal stress σ₁, and the relation between σ₁ and ρ is expressed by the exponential function.
(4) The equations in the theory of compacting metal powder could be established.