Patent ID: 8430608

Claim:
A drill having a front end and a rear end, comprising: a body at the rear end, a cutting point at the front end with a cutting edge where the cutting point with the cutting edge is integrally extended from the body, and a plurality of grooves concavely formed on outer surfaces of the cutting point and the body for composing a rake face of the cutting edge, thereby cutting a workpiece with the cutting edge when rotating about a center axis, wherein an intake hole is formed inside the body and the cutting point, where the intake hole is extended from a rear end of the body to the cutting point, wherein the intake hole has a circular cross-section and has a diameter smaller than a diameter of the body and larger than a bottom diameter of the groove and has an opening which is open from the groove towards the outside, where the bottom diameter is a diameter of a cylinder tangent to the plurality of grooves at a deepest point of each of the grooves, wherein a front end of the opening is positioned within the cutting edge, and a cross sectional area of the opening perpendicular to the center axis is smaller than a cross sectional area of the intake hole perpendicular to the center axis, and wherein an aspiration process is carried out through the intake hole with use of negative pressure, thereby aspirating chips generated during the cutting of the workpiece from the opening.