Two-piece rotary metal-cutting tool and method for interconnecting the pieces

A method of attaching a drilling head to a drill body, said drill body having a longitudinal axis and first and second opposed ends, one of said opposed ends comprising a centrally disposed dovetail-shaped recess, and at least two circumferentially spaced projections, each of said projections having a stop surface;

• said drilling head having first and second opposed ends, one of said opposed ends comprising a cutting portion, and the other of said opposed ends comprising a dovetail-shaped projection, said drilling head further comprising at least one stop surface;
• wherein said method comprises:
• inserting said dovetail-shaped projection into said dovetail-shaped recess;
• and
• rotating said drilling head relative to said drill body such that the at least one stop surface on said drilling head comes into engagement with at least one of the stop surfaces on one of the projections.

A method for mounting a cutting portion to a tool body to form a metal-cutting rotary tool, the tool body including a shank portion;

• a front surface, and rear chip flutes formed in an outer surface of the tool body;
• the cutting portion including a support surface abutting the front surface, a cutting surface having cutting edges, and front chip flutes formed in an outer surface of the cutting portion;
• one of the tool body and cutting portion including longitudinal projections, and the other of the tool body and cutting portion including circumferential recesses, each recess communicating with a respective flute and extending less than 180 degrees;
• the method comprising the steps of:
• A) converging the cutting portion and tool body longitudinally toward one another to bring the projections into respective ones of the flutes that communicate with the circumferential recesses;
• and
• B) effecting relative rotation between the tool body and cutting portion to cause the projections to enter respective ones of the recesses to bring the front flutes into alignment with the rear flutes, and to bring a stop surface of each projection into longitudinally opposing relationship with a stop surface of a respective recess for defining a dovetail-shaped bayonet connection preventing longitudinal displacement of the cutting portion relative to the tool body.