Drill bits are often used by everyone, but have you fully analyzed them? What is the name of each part of it? What are the characteristics? What should I do if it breaks? What should I do if there are burrs? Now I've sorted it all out for you, take it away~
All-round anatomy drill
Drill bit name
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professional title
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①Helix angle γ: Different models have different angles, generally 10°~40°.
②Blade: mainly plays the role of guidance and extrusion.
③Blade: The part between the edge and the groove, but lower than the edge, reducing the cutting force (friction).
④ Chip flute surface: Sometimes it is the rake face, the surface through which chips flow.
⑤Drill tip angle: the intersection point between the land and the cutting edge.
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drill bit angle
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⑥Main cutting edge: The angle between the two main cutting edges is the vertex angle б, the real cutting part.
⑦Front surface: The surface that forms the relief angle α.
⑧ Chisel edge: The part connecting the two cutting wedges, which bears 50% of the cutting force (axial direction).
⑨Blade clearance: Reduce the friction between the drill bit and the workpiece.
⑩Chip removal groove: Large space, conducive to chip removal.
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Orifice chip and burr issues?
Improved by reducing the drill tip angle so that the drill tip bears against the width and height of the workpiece.
Smaller drill point angle 118°
1. Radial force component, poor radial stability.
2. Small axial force.
3. Non-ductile materials reduce chipping.
Larger drill tip angle 135°~140°
1. Large axial separation and good radial stability.
2. Greater feeding capacity.
3. Soft sticky material to reduce flash.
4. The roundness, diameter tolerance and straightness of the hole are better.
Peripheral chamfer drill tip
1. Reduce chipping.
2. It has the advantages of a large drill tip angle drill bit.
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Drill bit application problems/measures
Drill tip wear
reason:
1. The workpiece will move downward under the action of the drilling force of the drill bit, and will rebound after the drill bit drills through.
2. The machine tool has insufficient rigidity.
3. The drill bit material is not strong enough.
4. The drill bit beats too much.
5. The clamping rigidity is not enough and the drill bit slides.
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measure:
1. Reduce cutting speed
2. Increase the feed amount
3. Adjust the cooling direction (internal cooling)
4. Add a chamfer
5. Check and adjust the coaxiality of the drill bit
6. Check whether the rear corners are reasonable
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chipped, damaged
reason:
1. The installation vibration of the drill bit is caused by excessive impact on one cutting edge.
2. The clamping rigidity of the workpiece is low, which occurs when drilling and cutting out.
3. The feed amount is too large.
4. The cutting speed is too high.
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measure:
1. Adjust the installation vibration to less than 0.02mm so that the two edges of the drill can perform drilling under balanced conditions.
2. Reduce the feed amount and reduce the impact when the drill bit is cut out.
3. If it is an indexable drill, change the blade material.
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built-up edge
reason:
1. Caused by the chemical reaction between the cutting material and the workpiece material (low carbon steel with high carbon content)
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measure:
1. Improve the lubricant and increase the oil or additive content.
2. Increase the cutting speed, reduce the feed rate and reduce the contact time.
3. If drilling aluminum, you can use a drill bit with a polished and uncoated surface.
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broken knife
reason:
1. The spiral groove of the drill bit is blocked by chips, and the chips are not discharged in time.
2. When the hole is about to be drilled (drilled through), the feed amount is not reduced or the machine is changed to manual feed.
3. When drilling soft metals such as brass, the back angle of the drill bit is too large and the front angle is not ground, causing the drill bit to automatically advance.
4. The drill edge is too sharp, resulting in edge chipping, and the tool cannot be withdrawn quickly.
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measure:
1. Shorten the tool replacement cycle.
2. Improve installation and fixation, such as increasing the support area and increasing the clamping force.
3. Check the spindle bearings and sliding grooves.
4. Use high-precision tool holders, such as hydraulic tool holders.
5. Use tougher materials.
