| 摘要 |
An annular cutter has a cylindrical sidewall 12a provided with teeth 16 around its lower end. The teeth form radially inner intermediate and outer cutting edges which are spaced apart circumferentially and which respectively extend from webs and lands at each radial location. The lands 28, 28 extend helically around the outer periphery of the cutter from the edges and define flutes 30 which extend circumferentially between the successive teeth. Every other land 28 or every land terminates in a plane substantially below the upper end of the cutter side wall to allow free chip dispersion during cutting. <IMAGE> |
