Method of Manufacturing a Hollow Externally Threaded Fastener

An anchor for being driven in a pre-drilled bore in a masonry or concrete member and engaging with a side wall of the bore, comprising:

• a. the anchor having an elongated main body with a main axis, the anchor having a forward end and a trailing end, an outer surface, and an internal bore that extends from the forward end to the trailing end;
• b. an external contour on the anchor for engaging with the side of the bore;
• wherein:
• c. the outer surface of the forward end has a camfer that tapers towards the forward end of the anchor;
• d. the outer surface of the trailing end of the anchor also has a camfer that tapers from the trailing end of the anchor to a portion of the anchor between the forward end and the trailing end where the outer surface of the anchor is formed with an external contour.

A method of forming a forming a hollow anchor a hollow blank, the method comprising:

• a. providing a die, the die including:
• a. a holder having a tapering inner surface with a plurality of raceways that extend along the tapering inner surface towards the bottom of the holder;
• b. a plurality of die inserts received in the race ways of the holder, the die inserts being able to slide along the race ways from a closed position where they are fully received in the holder and an open position where they are at an elevated position in the holder, the die inserts having inner surface which define a cavity where there is open space between the die inserts when they are in a closed position;
• c. a mandrel that can be received in the cavity between the die inserts when the die inserts are in the closed position, the mandrel having an outer diameter that widens from the bottom of the mandrel to the top of the mandrel;
• wherein
• d. profiling is provided on the inner surfaces of the inserts that forms a radial outer contour on the hollow blank when a mandrel is inserted through the hollow blank received in the cavity between the die inserts and causes plastic deformation of the material of the blank;
• b. moving the die inserts in the holder into an open position;
• c. placing the hollow blank in the cavity formed by the die inserts, the hollow blank having an internal bore an external surface, and a trailing end;
• d. moving the die inserts into a closed position;
• e. guiding a mandrel through the internal bore of the blank such that the mandrel protrudes all the way through the blank and the passage of the mandrel through the blank causes the material of the blank to be extruded outwardly into the profiling provided on the inner surface of the inserts forming an external contour on the outer surface of the blank;
• f. reversing the direction of the mandrel to remove the mandrel from the trailing end of the blank;
• g. moving the die inserts into the open position;
• h. extracting the hollow blank from the die inserts.