Broaching machine for external broaching of rotor

A broaching machine for broaching an outer surface of a rotor assembly by feeding a broach in a broaching direction parallel to an axis of rotation of the rotor assembly, said rotor assembly including a lobe-type rotor having a pair of lobes so as to form an external cross-sectional profile similar in shape to that of a peanut shell and forming said outer surface, and a support shaft which projects from opposite end faces of said lobe-type rotor in opposite directions parallel to said axis of rotation, said broaching machine comprising:

• a backing plate for backing said rotor assembly such that said backing plate is held in contact with one of said opposite end faces of said lobe-type rotor at which said broach terminates a broaching cut in said broaching direction;
• a positioning pin extending from said backing plate toward said one end face of said lobe-type rotor and engaging a positioning hole formed in an end face of one of said pair of lobes of said lobe-type rotor, thereby positioning said rotor assembly in a circumferential direction thereof;
• and
• means for centering said rotor assembly to align said axis of rotation thereof with a line of feed of said broach in said broaching direction, said means for centering said rotor assembly comprising a first centering device which includes a center portion engageable with one of opposite ends of said support shaft so as to hold and center said support shaft at said one end thereof, and a second centering device including a V-block and a retainer block which are engageable with the other end of said support shaft so as to hold and center said support shaft at said other end thereof.