Twist drill is the most commonly used cutting tool, twist drill to sharpen sharp, should pay attention to some points:
Twist drill bit is a commonly used drilling tool for machining. Although the structure is simple, it is not an easy thing to really sharpen it. close
The key is to master the methods and skills of sharpening, the method is mastered, the problem will be solved. Here I introduce the manual sharpening skills of twist drill.
The top Angle of the twist drill is generally 118°, and it can also be regarded as 120°. Grinding drill mainly master several skills:
1. The cutting edge should be flat with the grinding wheel surface.
Before grinding the bit, the main cutting edge of the bit and the grinding wheel face should be placed on a horizontal surface, that is, to ensure that when the cutting edge touches the grinding wheel face, the entire edge should be ground.
This is the first step in the relative position of the drill bit and the grinding wheel, and then slowly lean against the grinding wheel face.
2. The axis of the drill should be tilted at an Angle of 60° from the grinding wheel surface.
This Angle is the front Angle of the bit, and the wrong Angle at this time will directly affect the size of the top Angle of the bit and the shape of the main cutting edge and the cross edge Angle. This refers to the drill shaft
The position relationship between the core line and the grinding wheel surface is 60°, and this Angle is generally more accurate. Here, pay attention to the relative horizontal position and Angle position of the drill before grinding
The two should be taken into account as a whole, do not ignore the positioning Angle in order to straighten out the cutting edge, or ignore the leveling edge in order to straighten out the Angle.
3. Grind the back of the cutting edge.
After the cutting edge contacts the grinding wheel, it is necessary to grind from the main cutting edge to the back, that is, the cutting edge of the drill begins to contact the grinding wheel, and then slowly grinds down along the entire back cutting surface. Drill bit
When cutting, you can gently contact the grinding wheel, first carry out a small amount of grinding, and pay attention to observe the uniformity of the spark, adjust the pressure on the hand in time, and pay attention to the cooling of the drill, no
It can be worn to the fire, resulting in discoloration of the cutting edge, and annealing to the cutting edge. When the cutting edge temperature is high, the drill should be cooled in time.
4, the cutting edge of the drill should swing up and down, and the tail of the drill can not be lifted.
This is a standard drill grinding action, the main cutting edge on the grinding wheel to swing up and down, that is, the hand holding the front of the drill bit to evenly swing the drill bit up and down on the grinding wheel face
Move. The hand of the handle can not swing, but also to prevent the rear handle to tilt up, that is, the tail of the drill can not be high above the horizontal center line of the grinding wheel, otherwise it will dull the cutting edge
Method of cutting. This is the most critical step, the drill grinding good and bad, and this has a great relationship. When it's almost done, start at the edge of the cutting edge and gently rub the back corner,
Make the back of the blade a little smoother.
5. Ensure that the tip of the blade is on the axis, and the two sides are symmetrical and slowly repaired.
After grinding one edge of the drill, then grinding the other edge, it must be ensured that the edge is in the middle of the drill axis, and the edge of both sides should be symmetrical. An experienced teacher will look at the light
Look at the symmetry of the drill point, slowly grinding. The back Angle of the drill cutting edge is generally 10°-14°, the back Angle is large, the cutting edge is too thin, the vibration is severe when drilling, and the hole is three-sided
Or pentagonal, the chips are needle-like; 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 rise is large, the drill bit is seriously heated, and even can not drill. after
The Angle grinding is suitable, the front tip is in the center, the two edges are symmetrical, and the chip removal is light, no vibration, and the aperture will not be expanded during drilling.
6. After grinding the two edges, pay attention to grinding the tip of the bit with a larger diameter.
After grinding the two edges of the drill, there will be a plane at the tip of the two edges, which affects the central positioning of the drill. It is necessary to reverse the Angle 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 corner of the grinding wheel, and pour a small groove against the tip of the blade at the root behind the blade. This is also an important point of centering the bit and cutting briskly. Look out
When sharpening the edge tip chamfer, it must not be ground to the main cutting edge, which will make the front Angle of the main cutting edge larger, directly affecting the drilling.
Of course, there is no certain formula for grinding the drill, and it is necessary to accumulate experience in actual operation, and through comparison, observation and repeated trial and error, the drill will be better.
