The drill is a cutting tool for drilling. It is usually made of high-speed steel. The working part is hardened to 62-65HRC after heat treatment. Generally, the drill consists of a shank, a neck and a working part.
1. Shank: It is the clamping part of the drill, which plays the role of transmitting power. The shank has two types: straight and taper. High torque (mainly the flat tail of the handle) is used for drills with a diameter greater than 12mm.
⒉Neck: It is used for retreating the drill when grinding the drill. The diameter of the drill is generally engraved on the neck.
⒊Working part: It includes guide part and cutting part. The guide part has two narrow, thread-shaped edge bands (edges or secondary cutting edges) and spiral grooves. The role of the edge is to guide the drill bit and to smooth the hole wall; the role of the two symmetrical spiral grooves is to remove chips and transport cutting fluid (coolant). The structure of the cutting part is shown in the wall chart and the real object. It has two main chip edges and a shank edge. The distance between the two main chip edges is usually 118 ° ± 2 °, which is called the apex angle. The presence of the chisel edge causes the file to increase axial force.