Patent ID: 7284935
Filing Date: 2007-10-23
Classification: B23C,Y10T

Abstract:
1. A rotary cutting tool comprising a body rotatable about a longitudinal axis and having a cutting end and an opposite end; a plurality of pairs of flutes forming cutting edges each of which is of such length as to extend from said cutting end of said body toward the opposite end thereof but terminate short of the opposite end of said body; the cutting edges of a first pair of said flutes being diametrally opposite one another; the cutting edges of a second pair of said flutes being diametrally opposite one another; the cutting edges of said first pair of flutes being circumferentially spaced from one another and from the cutting edges of said second pair of flutes at said cutting end of said body; each of the cutting edges of said first pair of flutes extending from said cutting end of said body at a uniform, corresponding helical angle; each of the cutting edges of said second pair of flutes extending from said cutting end of said body at a non-uniform, corresponding helical angle different from that at which the cutting edges of said first pair of flutes extend; the helical angle at which each cutting edge of said second pair of cutting edges extends varying uniformly in a direction commencing at said cutting end of said body; the cutting edges of said first and second pairs of flutes being of such length and the helical angle of the cutting edges of said second pair of flutes being such that at a zone between opposite ends of said cutting edges of said pairs of cutting edges the circumferential spacing between the cutting edges of said first and second pairs of flutes corresponds to that at said cutting end of said body.