Fried Dough Twists drill is a commonly used drilling tool with simple structure. Grinding the drill edge is very important for workpiece processing, but it is not easy to grind it properly. The key lies in mastering the methods and techniques of blade grinding. With the mastery of these methods and the experience of multiple blade grinding, one can effectively grasp the grinding scale of the drill bit.
Before grinding the drill bit, first place the main cutting edge of the drill bit on a horizontal plane with the grinding wheel surface, 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.
2. This angle 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.
3. After the cutting edge contacts the grinding wheel, it should be ground from the main cutting edge to the back face, that is, starting from the cutting 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.
4. This is a standard drill bit grinding action, where the main cutting edge swings up and down on the grinding wheel, meaning that 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.
5. After grinding one edge, grind the other edge, ensuring that the edge is in the middle of the drill axis and the edges on both sides are 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 back 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.
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