Patent ID: 6045305
Filing Date: 2000-04-04
Classification: B23B,Y10T

Abstract:
A helically fluted twist drill device for cutting materials, said device comprising:a shank having a first and a second end;a cylindrical core having a first diameter and a first and a second extremity, said core and said shank having a common axis of rotation, said core extending coaxially relative to said shank and from said second end of said shank, said second extremity defining a point;at least three portions extending helically outwardly away from said core so that said portions define a second diameter, the arrangement being such that adjacent portions define therebetween a surface of a helical flute;each of said portions further defining a helical bore connected to a source of a cutting fluid for permitting a flow of the cutting fluid through said bore from said shank towards said point, the arrangement being such that at least three bores extend from said first end of said shank to said point so that in use of said device, the cutting fluid conveys the materials from the vicinity of said point through each flute towards said shank;said first diameter having a dimension within a first range which is 20-35% of a dimension of said second diameter; andsaid surface being machined such that each surface is of S-shaped configuration when viewed from said first end towards said point in a direction parallel to said common axis; andsaid surface in cross section from a first location on said second diameter defines a positive rake angle from a radius of said second diameter passing through said first location.