Can you sharpen drills?I only learned it today, so hurry up and learn

Drill grinding training materials

1. Types and characteristics of drill bits

1) Type

1.1High-speed steel drill (ordinary drill)

Mainly use high-speed steel W series and Mo series materials

1.2. (Alloy drill bit)

Use tungsten titanium (YG), tungsten titanium cobalt (YT) materials

Physical and mechanical properties of high-speed steel and cemented carbide materials

 

2) Features

The characteristics of cemented carbide drills: high hardness, fast heat conduction, good toughness, good elasticity,

Disadvantages of cemented carbide drills: poor impact resistance and poor wear resistance.

The advantages and disadvantages of high-speed steel drills are opposite to those of carbide drills..

Second, the structure of the drill bit

2.1 Spiral groove:It is set to discharge the chips, its size should enable the chips to be discharged smoothly, and it should have a helix angle.The helix angle of the groove varies according to the type of workpiece material.For hard materials, the angle should be small, for soft materials, the angle should be large.Ordinary drill bits for steel processing, the helix angle is about 30 degrees.

2.2 The top angle of the drill bit: The tip angle of the drill is small, although it is easier to cut into the workpiece, but its disadvantage is that the cutting edge becomes longer, the required power increases, and the cutting edge rake angle decreases, and the life is shortened.Therefore, the top-pointed drill is used in hole processing of soft materials.Usually for general steel materials, the vertex angle is about 120 degrees.

 

2.3 working part

The depth of penetration of the drill when drilling

2.3 neck

Equivalent to undercut

2.4 handle

Used for drill clamps

2.5 cutting part

The length of the top angle of the drill bit

2.5 Note: 1-12cm without neck, larger than 12cm with neck (currently the largest straight shank drill is 20mm).

(Illustration of various parts of the drill bit)

2.5.1 6.45 30 60

Effective length of drill = 30

Handle length=(60-30)

Diameter=6.45

Three, the scope of application of the drill

High speed steel: often range brass/aluminum alloy

Cemented carbide: common range of copper

4. How to change the drill bit to ensure that the depth of the hole drilled by the second drill bit is the same as that of the first drill bit

Specific steps

1. Grinding the drill

2. Measure the h value of the cutting part of the drill bit through the projector

h=The distance from the tip of the drill to the cutting point

3. Find the benchmark (how to do it)

3.1 block

3.2 Call the external knife (TXXXX)

3.3 The end face of the workpiece (Z0.0)

3.4 Withdraw the cylindrical knife to a safe point (G28U0.0)

4. Calculate the depth of the hole = h + working part (only need to modify the value of h in the instruction, and the hole depth setting remains unchanged)

5 Examples (BO18C drilling program)

T1313

#100=h

G0G99Z-3.0

X0.0

Z-1.0

G83Z[h+the actual depth of the hole]Q2000F0.06

G80

G0X38.

M1%

5. How to improve the processing path of the drill bit and the characteristics of straight groove drill and flat drill

1) Chip divider

Function: Play chip breaking function, small cutting force, suitable for processing copper and aluminum parts.

2) Straight flute drill

Function: poor chip removal, wear resistance, strong impact resistance, guiding role (can reduce part of the process), fast feed, slow processing.Suitable for brass processing.

3) Flat drill

Function: sharp, good chip removal, poor impact resistance, easy to break, slow feed, fast processing.Suitable for brass processing.

Six, the characteristics of the chisel edge and the method of grinding the chisel edge

6.1: Features

6.1.1 chisel thickness

1) Not sharp, chip removal is not smooth, easy to eccentricity, fast wear

2) Good orientation and easy control of the aperture

3) It is suitable for brass, but not suitable for processing red copper. If processing red copper, the workpiece is easy to burn, and the working part of the drill is easy to break in the hole of the workpiece.

6.1.2 thin blade

1) Good chip removal, easy to crack, poor guidance.

2) The aperture is not easy to control

3) Suitable for copper

6.2 grinding method

6.2.1 The chisel edge grinding method of ordinary twist drill

1) When improving the axial force on the chisel edge of the drill bit during processing, it is necessary to overcome the harsh cutting conditions such as the negative rake angle at the chisel edge.

2) When the chisel edge is processed, the chisel edge is sharpened in the form of a large cut to shorten the width of the chisel edge, so that the chisel edge of the drill core and the main cutting edge are close to the cross, reducing the axial force during drilling and the rotation during drilling. Moment.

3) After the axial force of the drill bit is improved, the centering accuracy is greatly improved.The use of the drill bit of this structure on the shell machining center can cancel the center drill under certain conditions, improve the processing efficiency and shorten the production cycle.(Specifically as shown below)

 

6.2.2 Chisel edge dressing method of cemented carbide drill law:

1) Adopt a large front angle of 140 to increase the cutting rake angle, change the force of the drill bit, reduce the cutting force, and make the processing smoother.

2) The chisel edge part of the drill is improved, the R-shaped cutting edge transition is adopted, and the chisel edge rake angle is increased on the basis of the R-shaped cutting edge. The core part is first cut and positioned before drilling, which realizes self-centering and cancels The process of the center drill meets the requirements of the position degree, and the edge is cut at the diameter to form a protective edge, so that the drill is not easy to cause chipping when drilling, and greatly improves the life of the drill..

Seven, the force analysis of the drill in actual processing

 

8. Wear and grinding methods of drill bits

8.1: The main distribution of drill bit wear:

8.2 The main steps of drill grinding:

1) Place the main cutting edge horizontally and parallel to the outer circle of the grinding wheel.

2) Keep the angle between the center line of the drill bit and the outer surface of the grinding wheel as ).3) Hold the head of the drill with your right hand for positioning support and add sharpening pressure.4) Hold the shank of the drill with the left hand and assist the right hand to swing up and down (purpose: grinding the back angle).5) The movements of the left and right hands must be well coordinated and coordinated.6) When sharpening, either from top to bottom or from bottom to top.7) After grinding one side, turn over 180 and grind the other side (the grinding method is the same as above).

8.3 Inspection method after drill bit grinding

During the sharpening process, the front angle, relief angle and chisel bevel angle of the main cutting edge are all ground at the same time.

1) After the drill is sharpened, visual inspection is generally used for inspection.During visual inspection, put the drill bit upright, stand in front of your eyes, look at the cutting edge with both eyes level, and the background should be clear.

2) Because the two drill blades are one behind the other during observation, parallax will occur. When viewing the two drill blades, the left edge (front edge) is often high..At this time, rotate the drill core 180 around the axis, and repeat this several times. If the results are the same, the symmetry is proved..

3) Ordinary twist drill sharpening, in order to prevent the cutting part from overheating and annealing, it should be often immersed in water to cool.

4) The choice of the top angle of the drill bit is generally 118-120 degrees .

5) Carbide drill bits cannot be immersed in water to cool.

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