METHOD AND APPARATUS FOR PRESSING HOLLOW PRODUCTS FROM POWDER COMPOSITIONS Russian patent published in 1999 - IPC

FIELD: powder metallurgy. SUBSTANCE: powder is poured to die and it is preliminarily compacted under specific load 0.016-0.008 MPa at simultaneously rotating punch round axis at least by two revolutions; realizing finish compaction at specific load set by predetermined density of product material. Preliminary compaction is also carried out due to reciprocation motions in different directions. Apparatus for performing the method includes die, punch for preliminarily molding whose profile is calculated according to equation K=V1/V1'=V2/V2'= =V3/V3', where K- factor of volumetric compaction of powder; V1/V1',V2/V2',V3/V3'- relations of volumes of preliminarily and finally compacted material in any separate circular cylindrical bands of blank and article. Apparatus also includes final compaction punch whose profile corresponds to inner contour of article. EFFECT: increased dimension accuracy, enhanced quality of products. 3 cl, 6 dwg, 2 tbl