The blade should be leveled with the grinding wheel surface. Before grinding the drill bit, the main cutting edge of the drill bit and the grinding wheel surface must be placed on a horizontal plane, which means that when the blade contacts the grinding wheel surface, the entire blade must be ground. This is the first step in the relative position between the drill bit and the grinding wheel. Once the position is set, slowly lean against the grinding wheel surface. The axis angle of the drill bit should be inclined 60 ° away from the grinding wheel surface, which is the sharp angle of the drill bit. If the angle is not correct at this time, it will directly affect the size of the top angle of the drill bit, the shape of the main cutting edge, and the oblique angle of the transverse edge. This refers to the positional relationship between the axis of the drill bit and the surface of the grinding wheel, which can be seen accurately by taking 60 °. Here, it is important to pay attention to the relative horizontal and angular positions of the drill bit before grinding. Both should be considered comprehensively, and do not neglect to adjust the angle or adjust the blade to adjust the angle. After grinding from the edge to the back, after the edge contacts the grinding wheel, it is necessary to grind from the main cutting edge to the back surface, that is, starting from the edge of the drill bit to contact the grinding wheel first, and then slowly grinding down the entire back face. When the drill bit is cut in, it can gently touch the grinding wheel. First, perform a small amount of edge grinding, and pay attention to the uniformity of the spark. Adjust the pressure on the hand in a timely manner, and also pay attention to the cooling of the drill bit. Do not let it grind too much, causing discoloration of the edge, and even annealing of the edge. When the temperature of the cutting edge is found to be high, the drill bit should be cooled in a timely manner. The edge of the drill bit should swing up and down, and the tail of the drill bit should not tilt up. This is a standard drill bit grinding action, where the main cutting edge should swing up and down on the grinding wheel, that is, the hand holding the front of the drill bit should evenly swing the drill bit up and down on the grinding wheel surface. The hand holding the handle cannot swing, and it is also necessary to prevent the rear handle from tilting upwards, that is, the tail of the drill bit cannot be raised above the horizontal centerline of the grinding wheel, otherwise it will make the cutting edge blunt and unable to cut. This is the most crucial step, and whether the drill bit is ground well or not is closely related to it. When the grinding is almost done, start from the edge of the blade and gently rub against the back corner to make the back of the blade smoother. Ensure that the blade tip is aligned with the axis, with both sides symmetrically and slowly trimmed. After grinding one edge, grind the other edge. It must be ensured that the blade is in the middle of the drill axis, and both edges must be symmetrical. Experienced masters will observe the symmetry of the drill tip in front of the bright light and slowly polish it. The back angle of the cutting edge of a drill bit is generally 10 ° -14 °. If the angle is too large, the cutting edge is too thin, causing severe vibration during drilling. The hole opening is triangular or pentagonal, and the chips are needle shaped; The back angle is small, and the axial force during drilling is large, making it difficult to cut in. The cutting force increases, resulting in a large temperature rise and severe heating of the drill bit, making it even impossible to drill. The back angle grinding is suitable, with the sharp point centered and the two edges symmetrical. During drilling, the drill bit removes chips quickly and without vibration, and the aperture will not expand.
After grinding the two edges, it is necessary to pay attention to grinding the sharp points of larger diameter drill bits. After grinding the two edges of the drill bit, there will be a plane at the sharp points of the two edges, which affects the center positioning of the drill bit. It is necessary to chamfer the corner behind the edge and grind the plane of the tip as small as possible. The method is to erect the drill bit, align it with the angle of the grinding wheel, and at the root behind the blade, pour a small groove towards the blade tip. This is also an important point for the centering of the drill bit and the ease of cutting. Be careful not to grind the chamfer of the cutting edge onto the main cutting edge, as this will cause the front angle of the main cutting edge to be too large and directly affect the drilling process.
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