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Continue to explain the shortcomings of several aspects of the twist drill
Release time:
2018-10-25
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First of all, the twist drill pipe is a professional drilling tool, so its application is also specific and has an irreplaceable role in a large area. However, it also has some defects of its own: it is known that the twist drill is mainly composed of the handle, neck and working part. Although the geometry of the twist drill is more reasonable than the flat drill, it still has the following shortcomings: 1. Compared with other types of cutting tools, the main cutting edge of the standard twist drill is very long, which is not conducive to chip separation and chip breaking. 2. The chisel blade is too long, and the rake angle of the chisel blade is a large negative value, reaching -54 ° ~-60 °, which will generate a large axial force. First twist drill
First of all, the twist drill pipe is a professional drilling tool, so its application is also specific, in a large area to complete the irreplaceable role, but also has some of its own defects:
It is understood that the twist drill is mainly composed of the handle, neck and working part, the geometry of the twist drill is more reasonable than the flat drill, but there are still the following shortcomings:
1.Compared with other types of cutting tools, the main cutting edge of the standard twist drill is very long, which is not conducive to chip separation and chip breaking.
2.The chisel blade is too long, and the rake angle of the chisel blade is very negative, up-54°～-60°, which will generate a large axial force.
First of all, the secondary angle of the secondary cutting edge at the edge of the twist drill is zero, resulting in increased friction between the secondary flank surface and the hole wall, rising cutting temperature, greater wear at the corner of the outer edge of the drill, and deterioration of the roughness of the machined surface.
4.The value of the rake angle at each point on the main cutting edge of a standard twist drill varies too much inside and outside. The rake angle of the main cutting edge at the outer edge of the drill bit is approximately 30°; and near the drill center, the front angle is about.-30°The front angle near the drill core is too small, resulting in large chip deformation and large cutting resistance. However, the front angle near the outer edge is too large, and the cutting edge strength is often insufficient when processing hard materials.
All in all, we usually see the twist drill has the above four points of defects, although there are shortcomings but does not affect its use in the relevant industry status!
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