Use of SLFET for design of flash gap with V-notched lands in a closed-die forging

The article concerns an influence of the geometrical flash gap parameters on the closed-die forging process. It is focused on the analysis of die forging process where used two kinds of flash gaps with V-notched lands (which have not applied in industries yet). The theoretical calculations were carried out using an authors method of sequential analysis, called slip line fields elemental technique (SLFET). Additionally, in order to determine the best shape of flash gap (depending on forming load and degree of cavity filling by metal) the poly-optimisation was made. The special geometrical model of forging process, which is assumed a forming by extrusion of parts with a central boss (in plane-strain conditions) was assumed in these analyses. Beside, the experimental verification of worked out forging model and obtained selected numerical results was done. That research was realized in laboratory conditions with the use of commercially pure lead workpieces and the special designed tools-set (which assures a forming in conditions similar to plane-strain state). Generally, the obtained experimental results confirm a satisfactory agreement with theoretical results.