1, identify the structure of the drill bit before grinding. Twist drill is divided into: cutting part, working part, neck and tail. The cutting part consists of main cutting edge, auxiliary cutting edge, transverse edge, rake angle and rake angle.
2. Prepare for safety protection and wear goggles. Hold the drill tip in the right hand and the drill handle in the left hand. When grinding two main cutting edges, the angle between the drill bit and the grinding wheel must be consistent, so as to ensure that the angle between the two drilling edges and the axis of the drill bit is equal.
3. When grinding, the drill bit and the grinding wheel grind back and forth at the same height as the center of the grinding wheel. Pay attention to grinding from the cutting edge position to the back face. The height of the drill shank is slightly lower than the drill tip, which can ensure that the rake angle is not high. Many novices often can't master the polishing of the back corner. When machining parts, the back angle contacts the parts before the cutting edge, so that the drill bit can't drill out iron chips.
4. The grinding of the back corner surface depends on the processing material. When processing materials with low hardness, because the materials are soft and the feed is large, it is necessary to grind a large back angle. The material with high hardness needs to bear a large force behind the edge, so the back angle is small, the force is good, the heat dissipation is good, and the edge is not easy to break.
5. The top angle of drill bit is usually 1 18 degrees, but different angles are also needed for actual machining. When grinding, you need to prepare an angle ruler or an angle template, and measure and adjust the grinding angle at any time to ensure that the angles and lengths of the two cutting edges are the same.
6. After the main cutting and grinding, it is necessary to grind the horizontal blade and polish the corner of the grinding wheel to a proper R. The purpose of grinding the cross edge is to center and reduce the torque and resistance.