BROACHING DEVICE AND METHOD

摘要

PURPOSE: To arrange a series of axially aligned bores into a true circle on a straight line even when they are made of different materials with different cutting charactersitics by forming longitudinally extending grooves slidably receiving the ribs of guiding means at the time of an advance on a broach. CONSTITUTION: A broach 11 is advanced through the openings 72 of aligned guides and bearing holes. Apexes of the ribs 74 of the openings 72 are coupled with the bottom sections of the grooves 66 of the broach 11 to guide the broach 11. When the broach 11 passes through bores, segments 69 of cutting edges 58 between the grooves 66 broach the bores but leave unbroached ridges. Segments of polishing edges 62 between the grooves 66 press the broached fan-shape sections of the bores to harden them but leave lugs as they are, then the left lugs are removed by a finishing broach.