PLASTIC STRAIN OF POWDER COMPONENTS IN UNCLOSED VOLUMES

During free compaction, extrusion, and bending of powder blanks, the m aterial is under conditions of nonuniform stress and strain and is sub ject to compression and tension. A form of plasticity theory is develo ped for such a body that includes the tension and compression applied to the material. The trends in this theory form the basis for three te chnological hot-pressing processes. They have been used to prepare sph erical layers for tractor hydraulic pump systems (the component is for med by compaction and at various stages is subject to various deformat ion schemes: uniaxial tension, free compaction, and hydrostatic nonuni form compression), and the same basis has been applied to gear forks f or tractors (forming in a semi-open die in two stages: in the first, t he state of stress varies from hydrostatic compression to uniaxial, wh ile in the second the material is densified under conditions of hydros tatic compression), as well as to the polar sprocket for an automobile alternator (the process involves plastic bending of the flat elements , with changes produced under tension and adjustment of the material o n a convex free surface followed by compression and densification on a concave one).