Powder metal axial and radial retention features for molding applications

Abstract

A powder metal insert for overmolding and method of making it has retention features on the outer surface extending from each end and angularly offset from one another.

We claim: 
     
         1 . A sintered powder metal insert for being overmolded by an overmolding material, comprising a body of sintered powder metal, the body having opposed end surfaces and an outer surface extending between the end surfaces, the outer surface having one set of retention features formed in it as spaced apart recesses extending from one end surface toward the other end surface and terminating short of the other end surface and having a second set of retention features formed in the outer surface as spaced apart recesses extending from the other end surface toward the one end surface and terminating short of reaching the one end surface, the first set being angularly offset from the second set so that the features of the first set are angularly between the features of the second set. 
     
     
         2 . A sintered powder metal insert as claimed in  claim 1 , wherein the features of each set extend axially a length so as to terminate short of axially overlapping the features of the other set. 
     
     
         3 . A sintered powder metal insert as claimed in  claim 1 , wherein the features extend longitudinally further than circumferentially. 
     
     
         4 . A sintered powder metal insert as claimed in  claim 1 , wherein each feature has a radially inward surface that is generally in the shape of a section of a cylinder. 
     
     
         5 . A sintered powder metal insert as claimed in  claim 1 , wherein each feature forms an end wall where it terminates at a blind end. 
     
     
         6 . A sintered powder metal insert as claimed in  claim 1 , wherein the outer surface is generally cylindrical. 
     
     
         7 . A sintered powder metal insert as claimed in  claim 7 , wherein the end wall is in a plane that is perpendicular to the axial direction. 
     
     
         8 . A sintered powder metal insert as claimed in  claim 1 , wherein the features of the first set do not intersect each other. 
     
     
         9 . A sintered powder metal insert as claimed in  claim 1 , wherein the features of the second set do not intersect each other. 
     
     
         10 . A sintered powder metal insert as claimed in  claim 1 , wherein the insert has a bore. 
     
     
         11 . A sintered powder metal insert as claimed in  claim 11 , wherein the bore has a non-round shape so as to be driven by a shaft. 
     
     
         12 . A sintered powder metal insert as claimed in  claim 1 , wherein the features of the first set do not intersect the features of the second set. 
     
     
         13 . A method of making a sintered powder metal insert as claimed in  claim 1 , including the step of compacting powder metal in a compaction tool set including upper tooling comprising an upper die and lower tooling comprising a lower die, wherein the one set of features is formed by one of the dies and the other set of features is formed by the other die. 
     
     
         14 . A method as claimed in  claim 13 , wherein the method includes the steps of filling a first cavity of the lower die with powder metal, bringing the upper die into abutment with the lower die and thereafter moving the powder metal in the first cavity so that it occupies cavities in both dies and thereafter compressing the powder metal in said cavities. 
     
     
         15 . A method as claimed in  claim 14 , wherein the compaction tool set includes at least one core pin that together with the lower die helps define the first cavity into which powder metal is filled, said at least one core pin defining a bore in the powder metal part upon completion of compaction of the part. 
     
     
         16 . A method as claimed in  claim 15 , wherein the core pin is stepped in shape so as to define a stepped bore of a larger diameter and a smaller diameter in the powder metal part upon completion of compaction of the part. 
     
     
         17 . A method as claimed in  claim 16 , wherein a tubular punch surrounds a portion of the core pin below the first cavity and has an end face that defines an end surface of the powder metal part upon completion of compaction of the part.