PISTON BLANK PRODUCING METHOD BY SHEET FORMING Russian patent published in 2006 - IPC B21D22/28 B21D51/16 

FIELD: plastic working of metals, namely manufacture of piston blanks used in disc brakes of motor vehicles.

SUBSTANCE: method comprises steps of forming blank in multi-position automatic press by multiple drawing without necking of flat blank; shaping concave bottom and outer joining radius of wall and bottom; performing two upsetting operations of blank walls; at second upsetting operation receiving blank with cone lateral walls in die with cone surface. Outer joining radius of wall and bottom is shaped by two transitions. At first transition outer angle between wall and bottom of blank is shaped with use of die having two cone surfaces of different conicity degree, punch and knocking out member with cone portion. Conicity of one surface of die of first transition coincides with conicity of cone surface of die for second upsetting. At second transition outer joining radius of wall and bottom is finally shaped with use of die with cone surface whose conicity coincides with that of die for second upsetting. Then blank is squeezed.

EFFECT: lowered metal consumption, improved strength of tool.

2 dwg