Method for making a drum rotor

Claim 1

In a method for manufacturing a drum rotor comprising a unitary cylinder-like drum having an axis and a plurality of axially spaced apart, enlarged annular rim portions, each rim portion including a radially outwardly extending portion having forwardly and rearwardly facing annular surfaces, each rim portion including a plurality of circumferentially spaced apart blade root slots extending therethrough from said forwardly facing to said rearwardly facing surface, the steps of: fabricating a plurality of separate drum sections, each section including at least one of said enlarged annular rim portions without said blade root slots therethrough, each drum section having an axis and including a cylinder-like wall extending axially outwardly from said enlarged rim portion; joining said drum sections together to form said unitary cylinder-like drum without blade root slots by inertia bonding or welding the end of said cylinder-like wall of one of said drum sections to the end of a cylinder-like wall of an adjacent drum section, said joined ends being at the same radius and said adjacent drum sections having a common axis; and after said step of joining, machining a plurality of circumferentially spaced apart curved blade root slots through each of said rim portions from said forwardly to said rearwardly facing surface using a circular broach, each of said slots being machined by rotating said broach about an axis located radially outwardly of said rim portion, whereby each of said slots is curved along its length in the plane of the broach.