The twist drill should want to grind sharp and can draw the dish, pay attention to some points:

1. The cutting edge is flattened with the sand side.

Before grinding the drill, you should put the main cutting edge of the drill on a horizontal plane, that is, when the blade is allowed to contact the sand side, the entire blade must be grinded. This is the first step in the relative position of the drill bit and the grinding wheel, and the position is slowly slowed down.

2. The axis of the drill should be obliquely 60 ° angle with the grinding wheel surface.

This angle is the sharp corner of the drill bit. At this point, the angle is not pair, and the size of the drill bit angle and the shape of the main cutting edge and the horizontal angle. Here is the positional relationship between the drill axis core and the surface of the grinding wheel, take 60 °, this angle is generally possible to see. Here, you should pay attention to the relative horizontal position and angle position before the drill bit blade, and the two should be intended. Do not ignore the intensity angle in order to set the blade, or ignore the horizontal edge.

3, behind the edge of the blade back.

After the blade is in contact with the grinding wheel, it is necessary to go backward from the main cutting edge, which is to start contact with the grinding wheel from the blade of the drill, and then move down along the entire knife surface. When the drill is cut into the grinding wheel, first make a small amount of edge grinding, and pay attention to observing the uniformity of the spark, adjust the size of the hand in time, pay attention to the cooling of the drill, can not let it grind, resulting in a cutting color And to the cutting edge annealing. When the cutting temperature is high, the drill bit is cooled in time.

4. The blade of the drill should swing up and down, and the tail of the drill must not be fond.

This is a standard drill bit grinding action, the main cutting edge is swing up and down on the grinding wheel, that is, the hand holding the front of the drill bit to swing up and down the drill on the sand wheel. The handle of the handle cannot be swung, but also prevent the back shank from rushing, that is, the tail of the drill bit cannot be highly posed above the centerline of the grinding wheel, otherwise the blade is blunt and cannot be cut. This is the most critical step, the drill bit is well grinded, and it has a big relationship with this. Almost when the grinding is almost, start from the edge of the blade, and then slightly lighter, let the edges are more smooth behind.

5, to ensure the sharp edge of the blade, the two sides are slowly repaired.

After the drill bit is worn, the blade is grinded, and the cutting edge must ensure that the cutting edge is in the middle of the axis of the drill, it is to be symmetrical. Experienced master will look at the symmetry of the drill tip to the shine, slowly carry out. The rear angle of the drill cutting edge is generally 10 ° -14 °, the rear angle is large, the cutting blade is too thin, the vibration is vibrated when drilling, the hole is in three or five sides, the chips is in needle, the rear angle is small, The axial force is very large when drilling, it is not easy to cut, the cutting force is increased, the temperature is large, and the drill is serious, and even can't drilled. The back angle angle is suitable, the sharp pair of front, two blade symmetry, when drilling, the drill draws are light, no vibration, and the aperture will not expand.

6, after the two eds are worn, pay attention to the drill bit of the drill bit to the diameter.

After the drill bit is worn, there will be a plane in the two blade sharp edges, affecting the center positioning of the drill bit, and needs to fall back in the back of the blade and smudge the plane of the blade tip. The method is to raise the drill bit, align the corner of the grinding wheel, pour a small slot on the blade behind the blade. This is also an important point for the drill center and cutting. Be careful when the grinding blade is not grinded on the main cutting edge, which will make the front corner of the main cutting edge to be large and directly affect the drilling.

The drill bit does not have a certain type, you need to accumulate experience in actual operations. By comparative, observation, repeated trial, we will give the drill bit better.