PURPOSE: To provide a stepped reamer for finishing the inner surface of a stepped hole in which the working precision is improved, and the rigidity of the tool is enhanced.
CONSTITUTION: Three chip discharging grooves 6 are formed on the outer circumferences of first-fourth edge parts 2-4 differed in diameter, and cutting edge tips 8-10 are provided on the top end ridge line part of a face 7 to radially provide differences in step. A support part is formed in a position differed in phase by 180° around the shaft center to each cutting edge tip 8-10 to receive the cutting load. The diameter of the groove bottom of the chip discharging grooves 6 is changed according to the diameter of each blade part 2-4 to enhance the rigidity. Further, a bottom blade is provided on the front surface of the top cutting edge tip 8.
MANABE TOSHIO
KUSUNOKI HIROYUKI
