OBRABOTKAMETALLOV technology Vol. 25 No. 2 2023 − ϑ ϑ = − − 1 1 1 . 1 / b b dl L (6) Moving the tool in the first stage of the ECAP process is only possible when the pore volume is reduced. At the same time, * s p and the relative density of the compressible porous mass increase. The dependence of the porosity ϑ on a load = τ / z s p p of the plastic flow of the compressible medium is represented as follows: − ϑ = + 3/2 1 (1 ) p . (7) Solving equations (6) and (7) made it possible to determine the change in the porosity of the titanium sponge and specific pressure as a function of plunger movement (fig. 5). a b Fig. 5. Change in the porosity ϑ of the compressible medium (a) and the specific pressure p (b) on the working plunger displacement dl/Lb. Fig. 6. Dependence of the plastic flow load p and side pressure b p on the a pressing tool on the porosity ϑ of the compacted medium: 1 – ϑ ( ) p ; 2 – ϑ ( ) b p Physical equations (3), and (4) were used to calculate the lateral pressure on the mold. The equation for calculating the lateral pressure has the following form = = − + ϑ − ϑ τ 2/3 1 ( 1 2 ln ). 3 s b b p p (8) The calculation results of ϑ ( ) p and ϑ ( ) b p are shown in fig. 6. Consider the stage of the ECAP process, in which the blank in the mold channel moves as a rigid plastic body. In this case, the deformation of the plastically compressible medium shape and volume changes is localized in the severe deformation layer (layer A-B). The layer thickness is Δh →0; the layer material is in a uniformly deformed state, which in the local coordinate system (n, τ, ς) can be represented by linear functions.
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