Design Details of Carbide Drill Bits

According to the diameter of the cemented carbide drill, the drill with an outer diameter of less than 4mm adopts a straight edge shape, and the cutting edge is a straight line; the design of the outer peripheral rake angle is negative, which can ensure the rigidity of the tool, the strength of the edge, and the low cutting resistance even if the diameter is small. These are two blade shapes. Carbide drills with an outer diameter of more than 4mm have a corrugated edge shape and a wide cutting flute design for better chip discharge.

1. Passivation treatment of cemented carbide drills

When manufacturing cemented carbide tools, the main cutting tip has certain burrs. If it is not removed, there will be a gap on the tip of the tool, which will aggravate wear during cutting and seriously affect the life of the tool. Through passivation of the main cutting edge, the tool tip forms an r-shaped arc, which reduces the probability of falling blocks and improves the surface quality of the hole.

The tool tip passivation treatment is to make the tip of the carbide drill into a small arc r to disperse the cutting resistance, eliminate the small serrations on the tip and ligament, and improve the rigidity of the tip. At present, the commonly used passivation methods include nylon brush passivation method, passivation machine strengthening method, suspension passivation method, and the more commonly used grinding machine passivation method.

2. The passivation machine strengthening method of cemented carbide drills

Install 18 carbide drill bits on the passivation machine at a time, add diamond grinding to its lower barrel, then insert the carbide drill into the diamond grinding, rotate, and passivate the carbide tip evenly after a few minutes . The amount of passivation is closely related to time. By strictly controlling the passivation time, the amount of passivation can be ensured, and the life of cemented carbide drills can be controlled and improved.

In order to prevent the main cutting edge of the China carbide drill bits from being too sharp, the main cutting edge needs to be negatively chamfered. Depending on the material to be machined, the minor chamfer of the main cutting edge is slightly different. The negative chamfer value of steel parts is 0.06-0.08mm, cast iron is 0.08-0.10mm, stainless steel is 0.02-0.03mm, and aluminum alloy is 0.01-0.015mm. The amount of negative chamfer passivation is directly measured with a dual-lens five-axis measuring instrument.

3. Coating treatment of cemented carbide drills

The coating treatment of the carbide drill bit has a great influence, the wear resistance after coating is increased, the surface quality of the hole is improved, the chip breaking and chip removal effect can be well improved, and the service life is increased by 5-10 times.