Method and apparatus for densifying powder metal preforms
AssigneeFederal-Mogul World Wide, Inc.
InventorsRichard Mark Woolf, Eric Riley
Life of this patent
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Abstract
A multi-stage forming tool for densifying the outer perimeter of post-sintered powder metal preforms includes a series of axially spaced die plates having different sized die openings arranged from largest to smallest. An oversized powder metal preform it is forced by a punch through the successive die openings causing the outer perimeter material to be displaced and densified. The space between successive dies allows for elastic recovery of the preform to maximize the compressive stress imparted to the preform at each die stage. A high density, high strength powder metal component results which is suitable as a replacement for wrought components in high strength applications such as transmission gears.
Claims17
A method producing powder metal articles comprising:
- compacting and sintering a powder metal preform having an outer perimeter portion thereof of predetermined shape to be densified;
- providing a multi-stage forming tool having a plurality of axially spaced forming die plates with die openings of the same general shape as that of the outer perimeter portion of the preform but being progressively smaller in size;
- and
- forcing the preform through the die openings from largest to smallest and plastically and elastically deforming the outer perimeter portion in stepped progression through the die openings to size and densify the outer perimeter portion and impart compressive stresses to the preform with the spacing between the die plates allowing elastic springback of the preform material between successive die plates.
A multi-stage forming tool for densifying compacted and sintered powder metal preforms having an outer peripheral portion of predetermined initial shape and size to be densified, said tool comprising:
- a plurality of die plates mounted in axial succession and being axially spaced from one another by a predetermined distance;
- and
- a corresponding plurality of die openings formed in said die plates having the same general shape as that of the outer peripheral portion of the preform to be densified but varying in size and arranged in axial succession from largest to smallest with each success die opening being smaller than the previous die opening by a predetermined amount.
A multi-stage forming tool for densifying and imparting compressive stresses to compacted and sintered powder metal gear preforms, comprising:
- a plurality of die plates arranged in axial succession having die openings formed in the general inverse shape of gear teeth and varying in size from largest to smallest;
- and spaces disposed between said die plates supporting said die plates in axially spaced relation to one another and defining axially enlarged expansion gaps between said die plates to accommodate at least partial recovery of an elastic component of deformation imparted to the preform as it passes through each of said die openings.
Dependencies are inferred from the claim text.