What are the main points of drill grinding?
The edge of the drill must swing up and down, and the tail of the drill can not stand up. This is a standard bit grinding action. The main cutting edge swings up and down on the grinding wheel, that is, the hand holding the front of the drill must swing the drill bit up and down evenly on the grinding wheel surface. The handle of the hand can not swing, but also to prevent the rear handle to go up, that is, the tail of the drill can not be high above the horizontal center line of the grinding wheel, otherwise it will make the edge of the grinding blunt, unable to cut. This is the most crucial step, the drill is worn well and bad, there is a lot to do with it. At about the same time, start at the edge of the blade and rub it gently in the back, so that the back of the blade is more polished.
Grind back from the edge of the blade. When the blade is in contact with the grinding wheel, it should be drawn back from the main cutting edge, that is, contact the grinding wheel from the edge of the drill bit and then slowly grind down the whole flank. Gently contact wheel bit penetration, advanced for less grinding, and observe the uniformity of discharge, timely adjustment of the size of the pressure on the hand, but also pay attention to the drill bit cooling, can not be allowed to wear too much, causing the edge to edge discoloration, annealing. When the blade temperature is high, the drill bit should be cooled in time.
Make sure that the edge of the blade is symmetrical to the axis and the sides are slowly repaired. When the edge is sharpened and the other side is sharpened, the edge must be in the middle of the axis of the drill bit, and the edges of both sides must be symmetrical. The symmetry of the experienced teacher will look to the light point, slowly grinding. Drill cutting edge angle is 10 DEG -14 DEG, after large angle, the cutting edge is too thin, when drilling vibration badly, orifice in three edge or pentagon, the chip is acicular; small angle, drilling large axial force, easy to cut, the cutting force increases, temperature rise drill, severe fever, or even drilling. For after the angle grinding, the tip of two edged, symmetrical, drilling bit, chip light, no vibration, no enlarged aperture.
