US 11,707,786 B2
Apparatus and method for internal surface densification of powder metal articles
Michael T Scott, Nashville, IN (US); Rajesh Parameswaran, Xenia, OH (US); Ricardo Lodeiro Guerra, Fussen (DE); and Christian Dennert, Pinswang (AT)
Assigned to PMG Indiana LLC, Columbus, IN (US)
Filed by PMG Indiana LLC, Columbus, IN (US)
Filed on Apr. 17, 2020, as Appl. No. 16/851,828.
Prior Publication US 2021/0323062 A1, Oct. 21, 2021
Int. Cl. B22F 5/08 (2006.01)
CPC B22F 5/085 (2013.01) [B22F 2998/10 (2013.01); B22F 2999/00 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A method of densifying a powder metal annular preform having a longitudinal axis, an inner preform surface, an outer preform surface and helical teeth on at least one of the inner and outer preform surfaces, each of said helical teeth having at least one flank, root and tip surface, said method comprising:
inserting the preform into a correspondingly dimensioned aperture formed between:
(i) a forming tool having an external surface correspondingly configured to the inner preform surface and coaxial with said longitudinal axis, and
(ii) a die disposed concentrically around and spaced apart from the forming tool coaxial with said longitudinal axis, the die having an internal surface correspondingly configured to the outer preform surface,
wherein at least one of the external surface of the forming tool and the internal surface of the die have forming teeth correspondingly configured and dimensioned to compress the helical teeth of the preform, and the one of the external surface of the forming tool and the internal surface of the die having forming teeth rotates about the longitudinal axis as the preform moves axially along the longitudinal axis and the helical teeth move through the forming teeth; and
forcing at least one of the preform, die and forming tool along the longitudinal axis, causing at least one of the preform, forming tool and die to rotate about the longitudinal axis resulting in the helical teeth of the preform being compressed by the corresponding forming teeth to selectively densify said surface of at least one of the flank, root and tip of the helical teeth.