Abstract: A method and apparatus for surface densification of powder metal annular preforms is described. A forming tool has external helical teeth corresponding to internal helical teeth of the preform. A die correspondingly configured to the external splines of the preform circumferentially surrounds the forming tool. The forming tool, die and lower punch(es) collectively define an aperture dimensioned to receive the preform. Upper punch(es) encase the preform in the aperture. Surface densification of the internal surface of the preform is achieved by movement of the preform axially over the forming tool. External splines of the preform and corresponding die splines direct the preform axially while internal helical teeth and corresponding forming teeth direct the forming tool to rotate as the preform moves. The forming teeth have varying dimensions in the circumferential and radial directions to apply compression and relaxation to densify the surface of the preform helical teeth.

Abstract: A method and apparatus for surface densification of powder metal annular preforms is described. A forming tool has external helical teeth corresponding to internal helical teeth of the preform. A die correspondingly configured to the external splines of the preform circumferentially surrounds the forming tool. The forming tool, die and lower punch(es) collectively define an aperture dimensioned to receive the preform. Upper punch(es) encase the preform in the aperture. Surface densification of the internal surface of the preform is achieved by movement of the preform axially over the forming tool. External splines of the preform and corresponding die splines direct the preform axially while internal helical teeth and corresponding forming teeth direct the forming tool to rotate as the preform moves. The forming teeth have varying dimensions in the circumferential and radial directions to apply compression and relaxation to densify the surface of the preform helical teeth.