Apparatus for molding tubular parts by isostatic compression

Apparatus for use in molding a tubular part by isostatic compression, the apparatus including a tubular casing having a cylindrical inner surface and an open end, and a cylindrical mandrel having an outer diameter smaller than the cylindrical inner surface of the tubular casing and being adapted to be disposed coaxially in radially spaced relation inside the casing, with one end of the mandrel extending outwardly from the open end of the casing, whereby an annular space is provided between the mandrel and the casing, the annular space between the mandrel and the casing being adapted to be filled to a predetermined location spaced inwardly from the open end of the casing with a powdered material suitable to be compressed to form such a tubular part, wherein the improvement comprises:

• a stop positioned on the mandrel adjacent to the open end of the casing when the mandrel is disposed within the casing in position for forming such a part;
• a cover having a hole therethrough sized to slidingly fit on said one end of the mandrel, said stop being located on the mandrel such that the cover simultaneously abuts the stop and the open end of the tubular casing when the mandrel is in the molding position;
• and
• a cylindrical spacer ring having an inner diameter slidably engaging the outer diameter of the mandrel and an outer diameter slidably engaging the inner surface of the tubular casing, the spacer ring being positioned adjacent the open end of the casing such that when one end of the spacer ring bears against powdered material filling the annular space between the mandrel and the casing to said predetermined location preparatory to isostatic molding of a tubular part, the other end of the spacer ring is spaced axially from the cover so that an annular expansion space is provided between the other end of the spacer ring and the coverto permit said powdered material to push the spacer ring along the mandrel toward the cover during isostatic compression of the powder between the tubular casing and the mandrel, whereby the spacer ring maintains a square edge and a desired wall thickness of a tubular part during isostatic compression molding of such a part.