Patent ID: 7618220
Filing Date: 2009-11-17
Classification: B23B,B23C,B23D,C22C,Y10T

Abstract:
1. A one-piece rotary tool for performing a plurality of operations on a work piece, said rotary tool comprises a hardened steel shank adapted to fit into a chuck of an electric drill, and an axially aligned drill bit and file portion having a forward portion adjacent to said drill bit and rear portion adjacent said shank and wherein the diameter of said file portion increases between said front and rear portions and in which the file portion has a shape of a hemisphere, and wherein the composition of said steel includes from 0.45 percent by weight to about 0.65 percent by weight carbon, about 2.25 percent by weight silicon, from 0.4 percent by weight to about 1.4 percent by weight molybdenum, from 1.5 to about 3.25 percent by weight chrome and less than 0.45 percent by weight sulfur and phosphorous, and wherein said file portion includes a plurality of crowned teeth about its periphery and wherein each of said plurality of teeth have a front cutting side and a back side and in which each tooth includes a plurality of sharp serrations extending longitudinal of each tooth and formed on the backside of each tooth adjacent the cutting edge thereof.