According to the different diameters of carbide drills, there are two types of blade shapes: drills with an outer diameter of 4mm or less adopt a straight edge shape, which is characterized by a design with a straight cutting edge and a negative peripheral rake angle, even if the diameter is small. Ensure tool rigidity, blade strength and low cutting resistance; drills with an outer diameter of 4mm or more adopt a corrugated blade shape and have a wider cutting groove design to better discharge chips.

(1) Passivation treatment

In the manufacture of cemented carbide tools, the main cutting edge will have certain burrs. If it is not removed, it will easily cause blockage and form a gap at the edge. This gap will aggravate wear during cutting and seriously affect the service life of the tool. . The passivation of the main cutting edge makes the cutting edge form an R-shaped arc, which reduces the chance of block dropping and improves the surface quality of the hole.

Cutting edge strengthening treatment is to make the cutting edge of the carbide drill form a small arc R, disperse the cutting resistance, and eliminate some fine serrations on the cutting edge and ligaments, thereby enhancing the rigidity of the cutting edge.

At present, the commonly used passivation methods include nylon brush passivation, passivation machine strengthening method, and suspension passivation method. The more commonly used is the polisher passivation method. Passivation machine strengthening method: load 18 cemented carbide drills on the passivation machine at a time, add diamond grinding sand to the barrel below it, and then insert the cemented carbide drill into the diamond grinding sand, rotate and revolve, several minutes After that, the cutting edge of the drill can be uniformly passivated. The amount of passivation is closely related to time. Strict control of the passivation time can ensure the amount of passivation, thereby controlling and improving the service life of the drill. Generally, passivation takes 30 minutes forward and reverse 5 minutes.

In order to avoid the main cutting edge of the cemented carbide drill bit from being too sharp and causing chipping, the main cutting edge needs to be negatively chamfered. For different processing materials, the main cutting edge side chamfer is slightly different. The negative chamfer value of steel 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 on a dual-lens five-axis measuring instrument.

(2) Coating treatment

The coating treatment of cemented carbide drill edge has a greater impact on it. After coating, the wear resistance increases, the surface quality of the hole is improved, which can well improve chip breaking and chip removal, and the service life is increased by 5-10 times. At present, the coating technology is developing rapidly. In the past, TiN coating was used. Now TiAlN, TiCN and composite coatings are used more.