Twist drill with spiral cutting back tool

Abstract

The invention discloses a twist drill with a spiral cutting back tool. The twist drill with the spiral cutting back tool comprises a cutting portion which rotates around an axis and a handle portion which matches with a jacket. Two grooves which extend from the front end of the cutting portion to the handle portion in a spiral mode and are sued for discharging cutting chips are formed in the cutting portion. The cutting portion is further provided with blade backs which are respectively connected with the periphery of the two grooves. The twist drill with the spiral cutting back tool is characterized in that the grooves form two spiral cutting back tool faces at the front end of the cutting portion, the two cutting back tool faces are intersected in a drill core position to form an S-shaped drill core cutting blade and two main cutting blades, the main cutting blade is connected with the S-shaped drill core cutting blade through a cutting blade connection portion in a smooth mode, each cutting back tool face begins from the main cutting blade and is formed by smoothly connecting a main back blade face, a transition face and a the cutting back tool face stop face. According to the twist drill with the spiral cutting back tool, the spiral cutting back tool faces are intersected to form the S-shaped drill core cutting blade which is connected with the main cutting blade in a smooth mode, stress concentration is greatly reduced, drilling load and centring capacity are further improved, and the twist drill with the spiral cutting back tool is easy to be widely popularized.

Description

technical field

[0001] The invention relates to a drill bit, in particular to a twist drill with a helical cutting flank. Background technique

[0002] The helical flank drill bit is a new type of drill bit compared with the flat flank, conical flank, cylindrical flank and other drill bits. Due to the cutting process of shear slippage, the axial penetration force is small during cutting; due to the limitation of the structure, the chisel edge of the drill bit such as planar, conical, and cylindrical drills is actually subjected to extrusion grinding, so the chisel edge It is easy to wear, and has a large axial penetration force during cutting; in addition, it also greatly enhances the centering ability of the drill bit.

[0003] However, due to the limitation of the technical level of the early helical flank drill bit, the excessively large relief angle at the junction of the chisel edge and the main cutting edge often caused edge chipping and weakened the strength of the d...

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