Drill steel and method of fabrication

摘要

A drill steel and method of making the drill steel which includes a tube which is opened up at one end by a first punch strike after which a male insertion element with external indentations is mounted on a second punch and driven partially into the opened end of the drill steel while simultaneously striking the drill steel at the end to collapse the walls of the tube around the element and into the indentations to lock the element in the tube. The finished drill steel thus has a male end to insert telescopically into the end of a similar steel to provide necessary extension devices.