The use of cemented carbide drillcan improve the tool life and cutting speed, for the processing of brittle hard materials, such as cast iron, insulation materials, glass, can significantly improve the cutting efficiency. Especially for difficult to process materials, such as high manganese steel, hard alloy drill bit must be selected to process. However, the application of cemented carbide drill is limited due to the vibration and instability in the process of drilling ordinary steel, which needs further research and exploration.

At present, cemented carbide drills are mainly made of insert blade shape, that is, the flat carbide blade is welded to the slotted cutter body. The most common percussion drill bit in our lives is this structure. The blade is commonly used YG8, the cutter body is 9SiCr, and the hardness is 50-56HRC after handling. Figure 12-14 shows the carbide taper shank twist drill.

Compared with tool steel twist drill, the main structural characteristics of cemented carbide drill are:

1) The drill core of the tool body is thick, d=(0.25-0.3) D; The guide section is short to improve bit stiffness and strength, reduce vibration during drilling and prevent blade cracking.

2) The chip sink is widened so that the chip discharge volume will not be reduced after the drill core is increased.

3) The amount of inverted cone increases. The amount of inverted cone on the full length of the blade is 0.01-1.08mm to reduce the friction between the edge and the hole during high-speed drilling.

4) Generally made of double helix Angle. The front Angle of the carbide blade part should be small, and the spiral Angle w=6-38; In order to improve the chip removal conditions, w-1520 was used as the guide part.