Standard drill is a very common drilling tool. It has simple structure and convenient grinding, but it is not as easy to really grind it well and master the grinding methods and skills. The key is the method and skill. If you master the method, the problem will be solved easily.
Although the commonly used standard bench drill bit only grinds the two main flanks and refines the transverse edge, it should ensure that the vertex angle, the oblique angle of the transverse edge and the length of the two main cuts are equal and the left and right heights are equal after grinding. Moreover, after grinding the transverse edge, it is indeed difficult to make the drill cut quickly and remove chips normally in the drilling process. After mastering the methods and skills, it is not very difficult to grind a qualified standard drill bit. Secondly, we should wear less and see more. Blind grinding makes us more blind. Only by grinding less, looking more, analyzing more and understanding more, can theory slowly guide practice. Less grinding means less grinding or even no grinding when there is no point. In this way, the waste caused by blind grinding can be saved, and you can also devote yourself to studying how to grind. To see more is to see the qualified standard drill bit with good grinding and all kinds of multifunctional drills with grinding defects. It's very important to watch quietly and carefully. Have a basic understanding of the "good" and "bad" of multifunctional drill.
"Less grinding" first means "no grinding". If you get the drill bit and grind it in a hurry, it must be blind grinding. Only by placing the position before grinding, can we lay a solid foundation for the "grinding" in the next step. This step is very important. The effect of using four sentences to guide the grinding process is better.
Edge leveling wheel face
This is a step in the relative position of the drill bit and the grinding wheel. The "edge" here refers to the main cutting edge, and "leveling" refers to that the main cutting edge of the sharpened part is in a horizontal position. "Wheel surface" refers to the surface of the grinding wheel. "Lean" means to move closer slowly. At this time, the drill bit cannot contact the grinding wheel.
Oblique setting out angle of drill shaft
This refers to the positional relationship between the axis line of the drill bit and the surface of the grinding wheel. "Sharp angle" is half of the top angle, which is about 60 °. This position is very important and directly affects the top angle of the drill bit, the shape of the main cutting edge and the inclined angle of the transverse edge. Pithy formula 1 and pithy formula 2 refer to the relative position of the drill bit before grinding. Both should be considered comprehensively. Do not neglect to set the bevel angle in order to set the edge, or ignore to set the inclined axis. These mistakes are often made in practice. At this time, the drill bit is ready to contact the grinding wheel when the position is correct.
Grinding the back from the edge
This refers to grinding slowly along the whole flank from the edge of the drill bit. This facilitates heat dissipation and grinding. On the basis of stabilizing and consolidating Formula 1 and formula 2, at this time, the drill bit can gently contact the grinding wheel for a small amount of grinding. During grinding, observe the uniformity of sparks, adjust the pressure in time, and pay attention to the cooling of the drill bit. When the grinding is restarted after cooling, continue to set the position of formula one and formula two.
Move the tail on the hem and don't tilt it
This action is also very important in the process of bit grinding. Pay full attention to the back angle of the drill bit and do not grind it too large or too small. When the drill bit with too large back angle is drilling, the orifice is trilateral or pentagonal, the vibration is severe, and the chips are needle shaped; The bit with too small back angle has great axial force during drilling, so it is difficult to cut in. The bit has serious heating and cannot be drilled.