Method of forming an insert in a workpiece for receiving a threaded fastener

Claim 1

A method of forming an insert in a work piece for receiving a threaded fastener therein comprising the steps of: a. forming a hole in the work piece with internally projecting, circumferentially spaced, longitudinally extending ribs on the work piece within the hole said hole having a first prescribed diameter; b. placing a tubular member having an annular seamless tubular side wall having a generally circular crosssection with a maximum outside dIameter a prescribed amount smaller than said first diameter and a head flange integral with one end of said side wall within said hole until said head flange engages said work piece, said side wall further defining a plurality of circumferentially spaced, longitudinally extending flutes therein, said flutes adapted to be slidably received on said ribs and engaged thereby to prevent rotation of said tubular member during step (c); and, c. forcing a coining mandrel having external threads thereon corresponding to the threads on said fastener along the inside of said side wall while rotating said coining mandrel to form external and internal threads in said side wall and force said external threads into intimate engagement with said work piece about said hole while forcing the side wall into the work piece about the preformed hole so as to deform the work piece about the hole into the external shape of the coined threads in the side wall.

Claim 2

A method of forming an insert in a work piece for receiving a threaded fastener therein comprising the steps of: a. forming a hole in the work piece with internally projecting, circumferentially spaced, longitudinally extending ribs on the work piece within the hole said hole having a first prescribed diameter; b. placing a tubular member having an annular seamless tubular side wall having a generally circular crosssection with a maximum outside dIameter a prescribed amount smaller than said first diameter and a head flange integral with one end of said side wall within said hole until said head flange engages said work piece, said side wall further defining a plurality of circumferentially spaced, longitudinally extending flutes therein, said flutes adapted to be slidably received on said ribs and engaged thereby to prevent rotation of said tubular member during step (c); and, c. forcing a coining mandrel having external threads thereon corresponding to the threads on said fastener along the inside of said side wall while rotating said coining mandrel to form external and internal threads in said side wall and force said external threads into intimate engagement with said work piece about said hole while forcing the side wall into the work piece about the preformed hole so as to deform the work piece about the hole into the external shape of the coined threads in the side wall.