Cold-working of steel by extruding or extrusion - moulding by means of a plunger and die

摘要

Sheet or similar material of alloyed or non-alloyed steel is provided with a raised or projecting hollow portion by allowing the sheet during extrusion to rise into a free bore provided in the extrusion plunger which cooperates with a flat die. The bore in the extrusion plunger may be surrounded by an annular projecting part of the plunger or be associated with a similar portion of the matrix.