Drill tip and drill bit

Abstract

A drill tip that is attached to the distal end of a drill bit and that performs drilling, the drill tip having a tip main body (1) provided with a proximal-end part embedded in a bit body of the drill bit and a distal-end part that tapers toward the distal-end side and protrudes from the surface of the drill bit. The surface of at least the distal-end part of the tip main body (1) is formed from a polycrystalline cubic boron nitride sintered compact (4) containing 70 to 95 vol% of cubic boron nitride sintered by a catalyst metal that contains Al and at least one of Co, Ni, Mn, and Fe.

Description

technical field [0001] The invention of the present application relates to an excavating blade which is attached to a front end portion of an excavating bit for excavation, and an excavating bit having such an excavating blade attached to the front end portion. [0002] This application claims priority based on Patent Application No. 2015-056106 filed in Japan on March 19, 2015 and Patent Application No. 2016-051788 filed in Japan on March 16, 2016, and the contents thereof are incorporated herein. Background technique [0003] As such an excavating blade, there is known an excavating blade in which the front end portion of a base body of a blade body made of cemented carbide is coated with polycrystalline diamond harder than the blade body in order to achieve a longer life of the drill bit for percussion excavation. The hard layer composed of sintered body. For example, in Patent Document 1, it is proposed that the above-mentioned front end portion of the blade body having...

AI Technical Summary

Problems solved by technology

[0006] However, polycrystalline diamond sintered body has higher wear resistance than cemented carbide, but its toughness is lower, so the fracture resistance is insufficient, and it may cause sudden chipping of the hard layer during excavation of superhard rock formations or defect

If the cemented carbide substrate is exposed due to the defect of the hard layer, the wear of the excavation blade will be accelerated at once, resulting in a shortened life of the excavation bit, making it necessary to frequently replace the excavation bit, resulting in a significant drop in operating efficiency

[0007] In addition, as described in Patent Document 2, in the method of adding carbide or nitride to the polycrystalline diamond sintered body to adjust the hardness and improve the toughness, the toughness will be improved due to the decrease in the bond between diamond particles. Hardness will be compromised

In addition, diamond sintered compacts cannot be used because they have a high affinity for Fe-based or Ni-based mines, and the heat-resistant temperature reaches about 700°C, so they cannot be used under conditions exposed to higher temperatures.

Also, due to its high hardness, it is difficult to regrind excavating blades whose hard layer is somewhat worn out to achieve effective use.

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